It is currently Sun Oct 20, 2019 6:14 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 24 posts ]  Go to page Previous  1, 2
Author Message
 Post subject: Re: Let's talk about cylinder head cracking!
PostPosted: Sat Sep 21, 2019 12:25 pm 
Offline
LOST Addict

Joined: Fri Jun 22, 2007 11:43 am
Posts: 4634
Location: Green Cove Springs FL
GordnadoCRD wrote:
Since we're not in a place to make our own heads (at least I'm not) out of a better material, the only things we can do to decrease this thermal current gradient is tune them back to the original F37 OEM tune, OR, increase the operating coolant temperature, which brings a mixed bag of tricks, and while it will decease the thermal gradient, I have no idea how much is necessary / enough.

Are you saying that the operating temperature of the engine should be increased?
To me, is seems that the operating temperature should be decreased. But I guess that depends on a variety of factors. If the operating conditions dictate the engine to run at 220F, it will do so, regardless of the operating temperature of the thermostat.

Or are you saying that the coolant/water ratio should be changed?
Or at least carefully monitor coolant ratio and condition?
Straight water has a greater heat capacity than coolant. But coolant has a higher boiling point.
I would never recommend running straight water (corrosion). Best to mix in some ratio like 50/50 or 60/40 (water/coolant).

It seems to me that coolant flow, or lack there of, is the main problem (i.e. inline thermostat).
After replacing my cracked head I had a theory that maybe the rearmost cylinders were running hotter than the front. So I stuck a temperature sensor on the side of the head between cylinders 3 and 4. Its not really the best sensor. Its not actually inside the head. Just stuck to the side. But it gives me some interesting data.
1. once everything is fully warmed up and I'm cruising at highway speeds, the cylinder head temperature is consistently ~20F cooler than what the coolant temp sensor is reporting.
2. when I slow down and have to stop at a light, cylinder head temp starts to increase. If I'm stopped long enough, cylinder head temp will eventually match the coolant temp.
This tells me that when then engine is operating at a higher rpm and there is good airflow through the radiator, the coolant is doing its job by pulling heat away from the head. Mainly due to increased coolant flow. (hey, its the best I've got to go with. Feel free to scrutinize those details however you wish)

Lastly, the symptoms of the cracked head were present before I did any kind of ECM tuning. Just using a stock tune. Although I was ignorant to those symptoms at the time.

_________________
Bought my '05 CRD on June 2nd '07, used with 29,000 miles.
intake elbow and EGR delete. 5 volt bosch glow plugs
Yeti stage 2 ECU tune. Straight pipe exhaust. DIY intercooler hoses
Provent and modified factory 180F thermostat
Replaced cylinder head (cracked) at 160,000 miles + ARP studs
2.5 inch lift, JBA upper arms, 235-85-16 tires.
Still love it.


Top
 Profile  
 
 Post subject: Re: Let's talk about cylinder head cracking!
PostPosted: Sun Sep 22, 2019 11:29 pm 
Offline
LOST Addict
User avatar

Joined: Sat Aug 27, 2016 9:12 pm
Posts: 2459
Location: Oregon Coast Dairy Country. Land of stumps, dumps, and "Liquid Pumps"
I guess what I'm saying, is there's more than one way to skin a R428.
What I'm NOT saying, is that I know what way is best. Or that I've thought of every solution.
The more detail you've given, the more I think of
inconsistency in casting
Inconsistency in material
EPA regulations requiring the domestic Jeep version of this engine to be run with coolant colder than the Euro/export versions. (which could explain why this problem seems to be more pronounced here, than in those versions.)

_________________
'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: Let's talk about cylinder head cracking!
PostPosted: Mon Sep 23, 2019 11:28 am 
Offline
LOST Newbie

Joined: Mon Jul 22, 2019 4:40 pm
Posts: 35
Location: Columbia, TN
Root cause....poor design.

As we all know the Dmax is aluminum headed as well.
Quote:
Time is an important factor in determining maximum acceptable EGT. The LLY/LBZ is rated for 1365 degrees F continuous and/or up to 1435 for 5 minutes or less. We've seen 1400 or a little more for completely stock LLY's during a Pull-Off here in Montana.

We also know that a Duramax can tolerate 1800+ degrees during a 1/4-mile run with lots of fuel and nitrous oxide, and for those willing to accept more risk. It's only there for a few seconds, which helps make it tolerable...

https://www.thedieselpageforums.com/tdpforum/showthread.php?t=23047

AND they don't drop valves, even after 500k miles of towing hotshot.

_________________
2006 Liberty CRD
2006 GMC LBZ


Top
 Profile  
 
 Post subject: Re: Let's talk about cylinder head cracking!
PostPosted: Mon Sep 23, 2019 12:15 pm 
Offline
LOST Addict

Joined: Fri Jun 22, 2007 11:43 am
Posts: 4634
Location: Green Cove Springs FL
Quote:
Root cause....poor design.


Can’t argue with that.
Unfortunately there’s nothing we can do about it.

I guess the best we can do is manage EGT and maintain good coolant flow.

_________________
Bought my '05 CRD on June 2nd '07, used with 29,000 miles.
intake elbow and EGR delete. 5 volt bosch glow plugs
Yeti stage 2 ECU tune. Straight pipe exhaust. DIY intercooler hoses
Provent and modified factory 180F thermostat
Replaced cylinder head (cracked) at 160,000 miles + ARP studs
2.5 inch lift, JBA upper arms, 235-85-16 tires.
Still love it.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 24 posts ]  Go to page Previous  1, 2

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 20 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:  
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group. Color scheme by ColorizeIt!
Logo by pixeldecals.com