It is currently Fri Mar 29, 2024 6:25 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sat Jul 22, 2017 5:38 pm 
Offline
LOST Addict

Joined: Tue Dec 16, 2014 9:33 pm
Posts: 1128
Location: Jackson,TN
I have changed two head gaskets in the last two weeks.
Neither one of them had a definite identifiable place they were leaking and one was pretty large volume leak
Both head gaskets separated the layers or at least partially separated them when removed head

Is it possible that coolant was going between the layers of the head gasket? What do you think?

_________________
05 Blu LIM, OME GDE Tbo, wk II 245/75/17, KC Lights, bull bar, 195K H TC
05 Blu Lim, Dayton, GDE HT, 255/75/18 , 210K , H TC
06 Bla Lim, GDE Eco, Destination AT 245/75/17, 151K, H TC
06 D Khaki Lim 126K wkII Eur TC
05 D khaki Lim 145k refurbishing
All CRDS: Fumoto, Lift , Fan Shroud mod, fuel head Gen II, SAMCOS,self TB, 2 Mic filt, Hayden


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sat Jul 22, 2017 5:58 pm 
Offline
LOST Addict

Joined: Fri Jun 22, 2007 11:43 am
Posts: 4962
Location: Green Cove Springs FL
Two head gaskets on the same engine?
Or two different engines?

Typical head gasket failure on the CRD is because the head bolts stretch and loose tension.
So yes, coolant can slip between the layers on the gasket.
This is why ARP head studs are recommended.

If you are having to replace the head gasket multiple times on the same engine, you likely have a cracked head.

_________________
U.S. Army Retired


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sat Jul 22, 2017 10:51 pm 
Offline
LOST Addict
User avatar

Joined: Thu Sep 06, 2007 9:51 pm
Posts: 6297
Location: Somewhere between Heaven and Hell... But it is really hot here on Earth...
This is also why when replacing the gasket it is suggested to replace with the two-hole and spray all four surfaces with copper kote sealant. Both sides of the gasket and the deck and underside of the head.

Take the opportunity to replace the valves too.

_________________
Proud supporting vendor of LOST Jeeps
TRAVELING CRD TECH. I come to you!
Need help? Just ask! I've taken it apart more than most.
Email jeep [at] maincomputer [dot] com - BOARD MESSAGING IS BROKEN
Over 125 CRDs currently driving with my timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sun Jul 23, 2017 4:01 am 
Offline
LOST Addict

Joined: Tue Dec 16, 2014 9:33 pm
Posts: 1128
Location: Jackson,TN
this is two different engines
Thats why I thought it might well be between the gasket layers
One had a small leak and was resealed with just ARP studs by coolant system pressure test while mostly disassembled but then I went ahead and took rest of the way down and replaced the gasket. This one is fixed and back running good.
BTW that one has 200k miles on it and cross hatch pattern from factory on liners was still easily visible on all cylinders

2nd one is one I bought about 6 weeks ago not running over a year , owner thought it was locked up.
They must have gotten it hot from blown head gasket and couldn't get it fixed or thought it wasn't worth fixing.
I actually got it for hood and door but when got home engine turned so I spent a day checking it out replacing some hoses and thermostat because the plastic barbs were cracked. Next day got it running and drove it about 10 miles under light load and lost a lot of coolant (water)
So now I have this one down. I really expected to find a cracked head on this one but it looks ok. I am planning on replacing gasket then putting it back together with ARP s enough to do coolant pressure test and if passes proceed with reassembly with new water pump TB etc
It has 147K on it now.

_________________
05 Blu LIM, OME GDE Tbo, wk II 245/75/17, KC Lights, bull bar, 195K H TC
05 Blu Lim, Dayton, GDE HT, 255/75/18 , 210K , H TC
06 Bla Lim, GDE Eco, Destination AT 245/75/17, 151K, H TC
06 D Khaki Lim 126K wkII Eur TC
05 D khaki Lim 145k refurbishing
All CRDS: Fumoto, Lift , Fan Shroud mod, fuel head Gen II, SAMCOS,self TB, 2 Mic filt, Hayden


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sun Jul 23, 2017 4:07 am 
Offline
LOST Addict

Joined: Tue Dec 16, 2014 9:33 pm
Posts: 1128
Location: Jackson,TN
I thought about the 2 hole gasket discussion and first one was a one hole original and i put a 2 hole.
This one is a no hole and I am going to go with 2 hole on it also.
Will see how it works out.

Thanks Flash and Geordi for your help!

Geordi I have a son starting at SCAD in Savannah, Ga and he will likely be driving one of the CRD s there if he has a problem and you r still in that area I will be looking you up. He isn't very mechanically inclined.

_________________
05 Blu LIM, OME GDE Tbo, wk II 245/75/17, KC Lights, bull bar, 195K H TC
05 Blu Lim, Dayton, GDE HT, 255/75/18 , 210K , H TC
06 Bla Lim, GDE Eco, Destination AT 245/75/17, 151K, H TC
06 D Khaki Lim 126K wkII Eur TC
05 D khaki Lim 145k refurbishing
All CRDS: Fumoto, Lift , Fan Shroud mod, fuel head Gen II, SAMCOS,self TB, 2 Mic filt, Hayden


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sun Jul 23, 2017 10:57 am 
Offline
LOST Addict
User avatar

Joined: Thu Sep 06, 2007 9:51 pm
Posts: 6297
Location: Somewhere between Heaven and Hell... But it is really hot here on Earth...
With the two-hole, that should offer an extra little bit of compression on the gasket for security. Hopefully there isn't any other issue but a coolant pressure test should illuminate that.

Replacing the valves is a good idea b/c while I don't have the official results yet, preliminary answer is that the valves aren't failing b/c of EGR or temperature... It is simple cyclical failure. They are opening and closing something like 3x10^9 times (something like 300 million times) and apparently that is just too many times for the stem to put up with. I wouldn't have thought it would be enough violence on the valve b/c it should just be spring pressure... But that is what the testing has shown at a molecular level.

On SCAD - what program? That is my grad school, and it is a great school. Expensive, but I think it pays dividends b/c of the quality of the education. I'm in Florida these days, but Sav is only hours away.

_________________
Proud supporting vendor of LOST Jeeps
TRAVELING CRD TECH. I come to you!
Need help? Just ask! I've taken it apart more than most.
Email jeep [at] maincomputer [dot] com - BOARD MESSAGING IS BROKEN
Over 125 CRDs currently driving with my timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sun Jul 23, 2017 1:59 pm 
Offline
LOST Addict

Joined: Tue Dec 16, 2014 9:33 pm
Posts: 1128
Location: Jackson,TN
He is doing 3D computer animation for film industry. I thought about at least exhaust valves but I may sell this one.
Is that what the metallurgy professor and students found or are finding?
Also did the aviation guy ask the maker in europe about run of valves for the crd if you have heard. ?

_________________
05 Blu LIM, OME GDE Tbo, wk II 245/75/17, KC Lights, bull bar, 195K H TC
05 Blu Lim, Dayton, GDE HT, 255/75/18 , 210K , H TC
06 Bla Lim, GDE Eco, Destination AT 245/75/17, 151K, H TC
06 D Khaki Lim 126K wkII Eur TC
05 D khaki Lim 145k refurbishing
All CRDS: Fumoto, Lift , Fan Shroud mod, fuel head Gen II, SAMCOS,self TB, 2 Mic filt, Hayden


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sun Jul 23, 2017 4:23 pm 
Offline
LOST Junkie

Joined: Fri Mar 20, 2015 2:11 pm
Posts: 801
Location: markham, ontario
If VM would learn from VW about how they make their TDI valves that would be great.


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sun Jul 23, 2017 8:20 pm 
Offline
LOST Addict
User avatar

Joined: Thu Sep 06, 2007 9:51 pm
Posts: 6297
Location: Somewhere between Heaven and Hell... But it is really hot here on Earth...
TKB4 wrote:
He is doing 3D computer animation for film industry. I thought about at least exhaust valves but I may sell this one.
Is that what the metallurgy professor and students found or are finding?
Also did the aviation guy ask the maker in europe about run of valves for the crd if you have heard. ?


He will have PLENTY of projects to do VFX for while in SCAD, and lots of opportunities when he graduates.

Yes, this is what the metallurgy professor and grad students found. Their class is over, I just don't have the printouts yet. But basically the failures seem to be entirely cyclical in nature rather than any kind of heat or scouring (wearing) related failures. I still suspect that poor metal could be at issue, but that is what they reported back.

I don't know the details of what the aviation guy found out. When I talked to Manley and Ferrara about custom valves, the price point was somewhere around $60 each for custom and that depended on the alloy. Once I know the specific composition of inconel, I can go back to Manley (they had better prices) and investigate the options with more intelligence. They *might* have something on the shelf that could work. MIGHT.


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sun Jul 23, 2017 8:42 pm 
Offline
LOST Addict
User avatar

Joined: Sat Aug 27, 2016 9:12 pm
Posts: 2505
Location: Oregon Coast Dairy Country. Land of stumps, dumps, and "Liquid Pumps"
geordi wrote:
Replacing the valves is a good idea b/c while I don't have the official results yet, preliminary answer is that the valves aren't failing b/c of EGR or temperature... It is simple cyclical failure. They are opening and closing something like 3x10^9 times (something like 300 million times) and apparently that is just too many times for the stem to put up with. I wouldn't have thought it would be enough violence on the valve b/c it should just be spring pressure... But that is what the testing has shown at a molecular level.

Criminy Jim! It has to be more than that. 3x10^9 works out to 10-12 thousand highway miles, and that's with no idle time.

(I'm not attacking you and I'm pretty sure we share the same interest here, so hear me out, please)

We know that this isn't the only engine that's suffered valve head separation. There seems to be a couple things that stand out to me, but in CRD's case, I'm only aware of what I've read on the forums.

First would be the frequency of failure. We know the Liberty's popularity was not the highest in 2005/06, and the CRD was a relatively small percent of those produced. Yet, this failure seems to be mentioned with nearly the same frequency as big block chevy's, an engine with many years in production and much higher numbers.
Is this because it really is a much higher percent failure, or because of how surprised people are at the relative expense of the repair?
You can buy and install a whole Reman long block big block for the price of just one one CRD head. Then you potentially have Piston, rings, liner, gaskets, tappets/lifters, timing belt, water pump, thermostat, filters, etc. And if you're not doing all the work yourself, you have a small fortune in labor cost on top of all that.
This tends to make people much more vocal about any said failure.

Second are, (and this is all speculation, not having actual metallurgical data), specific materials, and specific design.
Are they failing due to flaws in materials? I tend to doubt this a bit, because failures due to materials are more like early OHV design failures.
Us old timers are more familiar with cracks/chunks coming loose from valve heads, low quality valve guides wearing their stem holes oval, and such. Improvements in both materials and design (Sodium valves, sintered metal seats, much higher machining accuracy) have made failure rates much lower than in our day.
This R428's valve seems to separate mostly at the stem-head union. To me, this lends more credence to the design theory.
Are the valve springs perhaps a great deal stronger than they need to be, slamming the valves closed with much greater than necessary force?
We already know that this engine was designed when available lubricants and fuels had higher levels of Zinc, Magnesium, and Sulfur, who's purpose was to provide some cushion-type function, for both valve-seat contact, and valve-guide contact.
Does lacking these elements create increased stress during valve closing events?
Was there simply not sufficient fudge factor, (overkill) designed in to compensate for natural statistical variations?
Is the head-stem union too small diameter to handle this shock over billions of events?
I wonder how much available valve guide thickness there is, to create a valve with a larger stem and same head?
Such a solution would add weight to the valve, so would doing this just create different problems, for, say, valve seats?

The more I drive this vehicle, the more I like it, and the CRD is a major part of what I enjoy. If there is some way to significantly lower the chances of catastrophic failure, it's something I'm interested in, and I'm pretty sure you share that feeling. But to do more than take random shots in a dark room, for me, I need data. This is the hope I have in your friend.

_________________
'06 Lbrty Sprt CRD 150K

Sasquatch
DSS Turbo
CAT-elimntr
Weeks Stg1&2 EGRfix
PV-200
BLING
vent gauges

IDParts
head
cams
rockers
Timing set
ARP studs
eTn1 GX2123 5v GPs

YETI Custom Tune
Flowmaster 8325508
Carter P76611M
GM 12611872
Hayden 2986
GM 15976889
PATC Custom Billet
2010 Ram Hemi Trans
Sonnax 44957
Transgo kit
Cooper 51770


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sun Jul 23, 2017 9:25 pm 
Offline
LOST Addict

Joined: Fri Jun 22, 2007 11:43 am
Posts: 4962
Location: Green Cove Springs FL
The ramp of the exhuast cam lobe should allow for a controlled closure of the exhaust valves.
The valve should not be slamming shut.

My assesment is:
1. Worn rocker arms/cam lobes are allowing the exhaust valves to slam shut
Or
2. Excessive heat is causing metal fatigue
Or
3. Poor manufacturing is leading to early failure

Clearly, not every crd owner is having to deal with broken valves.
Lots of CRDs are now over 200k miles without breaking a valve.

_________________
U.S. Army Retired


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sun Jul 23, 2017 9:30 pm 
Offline
Lifetime Member
Lifetime Member

Joined: Sat Apr 01, 2006 9:38 pm
Posts: 12988
Location: Colorado Springs
rankom wrote:
If VM would learn from VW about how they make their TDI valves that would be great.

Nobody should be taking anything from VW until they can actually produce a diesel that can pass emissions.


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sun Jul 23, 2017 9:47 pm 
Offline
LOST Addict
User avatar

Joined: Sat Aug 27, 2016 9:12 pm
Posts: 2505
Location: Oregon Coast Dairy Country. Land of stumps, dumps, and "Liquid Pumps"
flash7210 wrote:
The ramp of the exhuast cam lobe should allow for a controlled closure of the exhaust valves.
The valve should not be slamming shut. Clearly, not every crd owner is having to deal with broken valves.
Lots of CRDs are now over 200k miles without breaking a valve.

True. (exactly my point) but enough are not, that it's become established reputation, nationwide.
But not with the rest of the world.
now,
WHY?
Most of us are wondering that.

So far, Geordi is the only one I know of with a foot making progress in that direction.
As far as making new custom valves, that's awesome, but it will be years before we know whether or not they will outlast the present valves, IF we ever do, because of the last line of the above quote..

EDIT.
With the domestic reputation of the R428, and problems like this and others, I'm wondering if that is why VMM decided against fixing this engine, and partnered with GM for the completely re-designed A428, AKA 2.8 Duramax I4
http://www.adandp.media/articles/diminutive-duramax-diesel-big-on-performance

_________________
'06 Lbrty Sprt CRD 150K

Sasquatch
DSS Turbo
CAT-elimntr
Weeks Stg1&2 EGRfix
PV-200
BLING
vent gauges

IDParts
head
cams
rockers
Timing set
ARP studs
eTn1 GX2123 5v GPs

YETI Custom Tune
Flowmaster 8325508
Carter P76611M
GM 12611872
Hayden 2986
GM 15976889
PATC Custom Billet
2010 Ram Hemi Trans
Sonnax 44957
Transgo kit
Cooper 51770


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sun Jul 23, 2017 10:02 pm 
Offline
LOST Member

Joined: Thu Oct 22, 2015 8:07 pm
Posts: 398
Location: Southeast Michigan
GordnadoCRD wrote:
The more I drive this vehicle, the more I like it, and the CRD is a major part of what I enjoy. If there is some way to significantly lower the chances of catastrophic failure, it's something I'm interested in
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=85965
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=86717
:SOMBRERO:


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Sun Jul 23, 2017 10:18 pm 
Offline
LOST Addict
User avatar

Joined: Sat Aug 27, 2016 9:12 pm
Posts: 2505
Location: Oregon Coast Dairy Country. Land of stumps, dumps, and "Liquid Pumps"
joe_ wrote:
GordnadoCRD wrote:
The more I drive this vehicle, the more I like it, and the CRD is a major part of what I enjoy. If there is some way to significantly lower the chances of catastrophic failure, it's something I'm interested in
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=85965
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=86717
:SOMBRERO:

No Joke!!
If this one blows up and the rest is still good, that's probably what will happen. Either the Cummins Re-Power 2.8 or the Durameister 2.8 (VMM A428)

EDIT OR if I feel really frisky, a 4.7HO V8!

_________________
'06 Lbrty Sprt CRD 150K

Sasquatch
DSS Turbo
CAT-elimntr
Weeks Stg1&2 EGRfix
PV-200
BLING
vent gauges

IDParts
head
cams
rockers
Timing set
ARP studs
eTn1 GX2123 5v GPs

YETI Custom Tune
Flowmaster 8325508
Carter P76611M
GM 12611872
Hayden 2986
GM 15976889
PATC Custom Billet
2010 Ram Hemi Trans
Sonnax 44957
Transgo kit
Cooper 51770


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Mon Jul 24, 2017 2:11 am 
Offline
LOST Addict
User avatar

Joined: Thu Sep 06, 2007 9:51 pm
Posts: 6297
Location: Somewhere between Heaven and Hell... But it is really hot here on Earth...
Don't quote me exactly on the number - I'm going from memory on that 3x10^9, but I do remember that he was talking something 300 -illion... Billion maybe? It worked out to be where they were failing, about 200k miles ish.

The thing is that they aren't separating where the head (coin) meets the stem. They also aren't separating where the friction weld is and the two dissimilar metals connect. They are failing in the MIDDLE of the alloy section!

I share the concern about the valve springs, but with hydraulic lash adjusters and roller rockers, they should be exactly following the cam and not closing by spring tension.

Getting custom valves made won't be difficult, it is only a matter of cost and knowing the specs of what we want for a temperature range. Right now... Replacing with stock gives you at least the same number of miles as you have already gotten, which puts most of these to 300k or 400k... Very respectable for an engine that was only certified and specified by Chrysler to VM for 125k miles.

Chrysler only cared about these lasting 125k miles. Ruminate on that for a while, and compare with the number of vehicles that are north of 150-200... And think about what corners we KNOW were cut.

And you want to buy another VM engine before knowing what is wrong with it? You are braver than I am.


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Mon Jul 24, 2017 3:01 am 
Offline
LOST Member

Joined: Sat Jul 11, 2015 11:05 am
Posts: 276
stiction...the valves are sticking due to stiction.

treat the engine to 16OZ of Militec1 and never have a valve stick and bind again. The turbo bearings also benefit.

mix Militec 1 with your next oil change oil.

_________________
Got Sheep?

2005 Jeep Liberty CRD 271'000+ KM's, ORM, Muffler Delete, MOROSO oil/air separator unit, 1000 CA battery, ARB Bull bumper, OME coils/shocks 2" lift. Custom BushRoo roof rack & Bush Joey hitch rack. Mobil1-301 oil filter & Mobil 1 DELVAC ESP 0W40 Full Synthetic oil, custom rear hatch cargo rack. RACOR 245 filterhead


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Mon Jul 24, 2017 3:13 am 
Offline
LOST Addict
User avatar

Joined: Thu Sep 06, 2007 9:51 pm
Posts: 6297
Location: Somewhere between Heaven and Hell... But it is really hot here on Earth...
And what does that have to do with a failure that is not within the valve guide? The alloy section never touches the valve guide.


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Mon Jul 24, 2017 4:46 am 
Offline
LOST Member

Joined: Sat Jul 11, 2015 11:05 am
Posts: 276
its my understanding (according to the machinist that redid my cyl head) that the valves are sticking in the valve guideways and on the valve seats. They had to rehone the guideways LARGER adn micro polish the valve stems to prevent them from sticking.

militec1 prevents that. Im pushing 60,000 KM+ of HARD , severe duty , with loads, on my rebuilt valve train. Smooth as greased butter.

_________________
Got Sheep?

2005 Jeep Liberty CRD 271'000+ KM's, ORM, Muffler Delete, MOROSO oil/air separator unit, 1000 CA battery, ARB Bull bumper, OME coils/shocks 2" lift. Custom BushRoo roof rack & Bush Joey hitch rack. Mobil1-301 oil filter & Mobil 1 DELVAC ESP 0W40 Full Synthetic oil, custom rear hatch cargo rack. RACOR 245 filterhead


Top
 Profile  
 
 Post subject: Re: Head Gasket OBSERVATION/ QUESTION
PostPosted: Mon Jul 24, 2017 11:37 am 
Offline
Moderator
Moderator
User avatar

Joined: Sat Aug 24, 2013 11:36 pm
Posts: 7158
Location: Central GA
Bushman5 wrote:
its my understanding (according to the machinist that redid my cyl head) that the valves are sticking in the valve guideways and on the valve seats. They had to rehone the guideways LARGER adn micro polish the valve stems to prevent them from sticking.
militec1 prevents that. Im pushing 60,000 KM+ of HARD , severe duty , with loads, on my rebuilt valve train. Smooth as greased butter.

Not to belittle anyones choice of oil additives; most everyone has their own special brew or mix they like and sware by.
Militec-1: At ~$40 bucks per 16 oz. I certainly hope it would be some super good quality stuff and perform as advertised. After reading, I found it has many great reviews in the gun world, just not a lot of info in the automotive world.
Some reviewers like it and some said it was not worth the cost as other available products did the same thing for much less. :roll:

Some on this forum including myself like and use Marvel Mystery Oil in both engine oil and mixed with the diesel fuel to help add lubricity to the low sulfur fuel we have nowadays to help protect the CP3 and injectors from metal galling...
MMO has been around for a very long time and has a well proven track record as a quality product!
I would imagine that MMO performs very similar treatments to the metal surfaces or pores to reduce friction as does the Militec-1?

But I do agree with you and I fully understand the phenomenon that a valve sticking in the valve guide due to stiction in this Interference engine could well cause a broken valve stem in the area reported by members on this forum. Some simply do not have the experience or training to fully understand the mechanics of all of this! :roll:
Honing or reaming valve guides, even newly installed ones is a standard practice by machine shops when rebuilding heads to ensure adequate/correct valve stem to valve guide clearance.
I have done it thousands of times in my career.
Remember, valve guide to valve stem contact receive very little if any lubrication as the valve stem seal prevents engine oil from getting to this area. Most replacement valve guides are made out of a bronze/brass mixture with an impregnated lubricant in the metal to improve lubricity and try and help prevent galling and / or seizure.

Another area of concern is heat transfer from the valve stem itself up through the valve guide and into the head where engine coolant can remove the heat.
Diesel engines as a general rule have a little looser clearances on both intake and exhaust guides than gas engines, and heads with sodium-filled exhaust valves usually require an extra .001 of clearance to handle the additional heat conducted up through the valve stems.
A valve transfers about 15 to 30 percent of its heat through the valve stem and into the head. On an exhaust valve where there is no cooling effect from the incoming charge air, there is only heating effect from the exiting exhaust gases, the valve to guide clearances are critical, because cooling through the stem is especially important for valve longevity.

So that being said, there is also a possibility that as the 2.8 engine ages with miles and wear, clearances open up between the valve stem and valve guide and heat cannot get properly transferred and removed allowing the valve stem to overheat in critical areas causing embrittlement which can lead to valve stem failure. :shock:

:SOMBRERO:

_________________
Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited :JEEPIN:
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount

98 Dodge Cummins 24 Valve


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 24 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group. Color scheme by ColorizeIt!
Logo by pixeldecals.com