| LOST JEEPS http://www.lostjeeps.com/forum/phpBB3/ |
|
| Valve failure research thread - We need your data! http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=84902 |
Page 2 of 10 |
| Author: | xtriggerman [ Wed Aug 10, 2016 1:39 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
This is certainly a most interesting thread. Thank you Geordi for getting this out of the shadows! But one thing that may be added to the mix is Towing. As a long time Dodge CTD owner, the fastest way to get to 1400F and beyond is get on a good hill and add lean boost with a couple few tons on the hitch. Iv always been annoyed about not having an EGT gauge on the CRD but we never tow with it either. I see this issue as a relationship with the EGR, restrictive exhaust and EPA mandated lean boost. Throw in a heavy foot with or even without towing and bingo, your chances of any kind of head gasket/valve failure increases. Moving a welded heat treated part into a crystalline structure with many high temp exposures and shock strikes against the seat.... in my mind its a wonder they last to 200K! I still need to do the ARP studs soon but seeing this new info here, an open exhaust is now on my list and maybe finding someway to run a bit of black smoke with stock boost at WOT. EGR was out of the picture at about 60K soon after I bought it with the GDE tune. These measures are the standard way to lower EGT's which may very well lower the chances of gasket failure to boot. |
|
| Author: | geordi [ Wed Aug 10, 2016 6:29 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
You may have it reversed in your mind, that knowledge that EGR use cools things and leaner-is-hotter are both concepts that are correct for gasoline but not for diesel. Diesels are a lean-burning fuel. When they are making smoke they are running HOT. Fuel = heat in a very real and direct way. Having a boost leak (EGR stuck open) or a program that runs rich makes much higher cylinder temperatures. This is why when a diesel is working hard and running hot, you reduce fuel or increase boost to lean out the mix, which cools down the combustion. Too much fuel and you risk melting a piston. On a gas engine it is exactly the opposite: when working hard and running hot, the potential for ping (detonation) is greater, so you increase fuel or reduce boost (if you have it) to make the mix rich, this cools the combustion. Not enough fuel and you risk melting a piston. So for us, we need to reduce the fuel, or increase the boost. Since the fuel map is based on the expected boost and not the actual (dumb design) then our best bet is to find and eliminate all the potential boost leaks that exist. The biggest ones are related to the EGR system. I recently found a picture of my CRD running down the road at 70mph, with the EGT probe that I had installed in the mouth of the turbo. This would be about 2-3 inches distance from the nearest exhaust valve, and maybe 5-6 inches from the furthest. I can't believe that the temps would drop that much from the outlet of each cylinder, but it was only reading 600 degrees! So if our exhaust valves are failing at such a low temperature... This has to be a major flaw somehow. Even the basic valves that Manley makes would range to about 1300 degrees. As far as eliminating the EGR to prevent head bolt failures, I don't see that happening. The head bolt failure is too consistent across the fleet, to basically eliminate most of the variables out of the equation other than simply age and poor selection of a fastener. I don't believe it is a question of IF a given CRD will experience a leak into the water jacket, just a question of when. The metallurgy results have not come back yet - Everyone can be confident that as soon as I know anything, so will you! |
|
| Author: | xtriggerman [ Thu Aug 11, 2016 12:58 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
If you see 600F on your EGT, its been said that is the perfect temp for a steady level run. It represents a perfect burn (most efficient) on a modern diesel engine. And I understand the EGR is used to cool the burn to reduce the high temp hydrocarbons but I hate the idea of what its end result is. Anyone who has cleaned a few TDI intake manifolds as I have will also have it high on the delete list. As far as running rich, I am relating what a whole lot of folks think on that specifically from the TDR web sight. Black smoke is unburned fuel and as such, pouring it threw the engine at high demand throttle actually cools the EGT's. Watch the drag vids like this one https://www.youtube.com/watch?v=1J2wkLTlh2U and you can see most of these guys run rich even after the full boost kicks in. Just why these valves are failing is a great undertaking and your efforts in this are highly regarded. |
|
| Author: | olypopper [ Fri Aug 26, 2016 12:59 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
xtriggerman wrote: If you see 600F on your EGT, its been said that is the perfect temp for a steady level run. It represents a perfect burn (most efficient) on a modern diesel engine. And I understand the EGR is used to cool the burn to reduce the high temp hydrocarbons but I hate the idea of what its end result is. Anyone who has cleaned a few TDI intake manifolds as I have will also have it high on the delete list. As far as running rich, I am relating what a whole lot of folks think on that specifically from the TDR web sight. Black smoke is unburned fuel and as such, pouring it threw the engine at high demand throttle actually cools the EGT's. Watch the drag vids like this one https://www.youtube.com/watch?v=1J2wkLTlh2U and you can see most of these guys run rich even after the full boost kicks in. Just why these valves are failing is a great undertaking and your efforts in this are highly regarded. xtriggerman, you are exactly 180 degrees off on your lean/rich understanding. Diesel engines that run very lean fuel/air are going to run with a low EGT. Diesel engines that run a very rich fuel/air are going to show high egt. It is exactly opposite of gasoline engines. Not flaming, just trying to educate. I've been on the TDR for many years and it's a great site and I play there quite a bit also. |
|
| Author: | rankom [ Sun Sep 04, 2016 5:14 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
well i see id parts has there valves on order (out of STOCK) i hope VM did little reading here and got good quality parts coming our way LOL |
|
| Author: | geordi [ Mon Sep 05, 2016 11:55 am ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
One would hope... But that is also why I have a new valve (both) included in the testing. Hope to have results soon, but it may have to be spring based on class schedule. Sent from my iPad using Tapatalk HD |
|
| Author: | GordnadoCRD [ Mon Sep 05, 2016 7:26 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
2.8 CRD - VM MOTORI Turbo Failure due to Motor Oil Failure. Bearing Failure Compressor Side, Caused Compressor backing plate mounting screws to back out into Compressor turbine wheel, and destroy the turbine wheel and bearing seal. No Valves actually failed, but just to be safe I installed a new factory head unit with all new valves, springs, rockers, hydraulic adjusters, and cams. I plan to refurbish the old head, cleaned, with all new valves, springs, and surfacing, and sell it, possibly on ebay. Anyone who wants the valves for analysis, unfailed, with 148k miles, please let me know. One thing I noticed is the valves and rockers have worn into matching pattern which would prevent the valves from rotating. This could be the cause of early failure. every other engine I've ever worked on has some type of feature that causes the valves to rotate as the engine runs, allowing even valve wear in the seats, and cam lobe wear with the lifters. This engine has no such feature. Gordon |
|
| Author: | flash7210 [ Tue Sep 06, 2016 7:21 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
Quote: Turbo Failure due to Motor Oil Failure. Which oil were you using? Quote: every other engine I've ever worked on has some type of feature that causes the valves to rotate as the engine runs, allowing even valve wear in the seats, and cam lobe wear with the lifters. No valve rotators on these engines. The CRD engine has more in common with a DOHC gasser than an old cam-in-block Cat/Cummins. |
|
| Author: | GordnadoCRD [ Fri Sep 16, 2016 5:41 am ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
The turbo was failed when I acquired the vehicle. The oil was, well, a high quality oil NOT designed for diesel use, and was well beyond it's service life. <edit> This was not the original turbo either. I am not certain of the maker, but it appears in every way and casting marks, same as the picture shown in ebay and sold by superturbo for this application. This engine definitely has design elements new and interesting from those of 3 decades past. The head I removed has no apparent damage, all valves and springs are still installed. I'm hoping I have no future need for this, and I'm wondering if it would be better to offer for sale as is, or to clean and install all new valves, etc? I also have a full set of new TTY head bolts if there is any market for them. |
|
| Author: | Patrick Henry [ Tue Sep 20, 2016 11:48 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
Great work there Geordi! The break on the first valve looks like classical brittle fracture. Hope that Dr. Dent can provide further insight after examination. I am like you, the 1st valve broken part probably cause the break of the 2nd exhaust valve. As I recall, I was cruising down the interstate at 75 mph when it abruptly loss power and I coasted to a stop. As for the past history, that jeep never experienced any kind of an over-temperature event. |
|
| Author: | Gypsy62 [ Tue Oct 04, 2016 2:38 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
Geordi, and others: I'm pulling my head this week. Given these exh. valve concerns, is there any reason to believe IDParts (oem?) valves are NOT an advisable replacement? Yes or no, I need to order asap to keep the ball rolling. I wish I could wait months for your heroic non-oem valve alternative(s) study results, but no can do. Unless I'm misreading the above data, it appears that a few of these failures occurred with only a few hundred miles on a post-op head. Yikes! Do we know how many of the head components were replaced at "rebuild"? Probably rockers/ARPs, but what about (IDParts?) valves/springs/keepers/spring caps-seats/seals? I was LJ-advised to replace the exh. valves. Given "wear" considerations, I was also thinking springs and keepers, but this thread impresses that the only suspect failure "issue" is the valves themselves. I'm not eager to throw P&L at non-issues unless they're genuinely preventative. Thoughts? Thanks to all! |
|
| Author: | flash7210 [ Tue Oct 04, 2016 8:32 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
At the moment, all thats available are the oem valves. So go with the ones from idparts. And I would just replace the exhaust valves and valve guide seals. |
|
| Author: | Bushman5 [ Sun Dec 18, 2016 10:31 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
any updates? curious why the valves do not rotate in the guideways like every other engine in the world. |
|
| Author: | lacabrera [ Mon Dec 19, 2016 11:23 am ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
flash7210 wrote: At the moment, all thats available are the oem valves. So go with the ones from idparts. And I would just replace the exhaust valves and valve guide seals. Has this set up got valve guide seals? Nether worked on a diesel engine that has them. No intake vacuum no seals required. There is no reason why the valves wouldn't rotate the same as any other engine. Ware on one side of the stem I guess could prevent them from rotating, unless I missed something on my rebuild. |
|
| Author: | geordi [ Sat Dec 24, 2016 2:03 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
Just to answer some of the questions - sorry for not getting back to this thread, there hasn't been a lot to report yet other than (thankfully!) no new valve failures that I've heard about. The testing is waiting for graduate students in the spring semester, this is a benefit as we will get much better and way more information than could have been afforded commercially. Like potentially tens of thousands of research dollars worth of testing. THANK YOU SO MUCH on behalf of the community!!! The reason the valves do not rotate (or might not - this is something of a suspicion rather than proven that I have seen) is that the rockers are roller rockers and not directly contacting the valve stem themselves. The only other engines I have direct experience with are Ford pushrods or the VW TDI. Pushrods are similar to the CRD in that the rocker presses directly onto the valve stem, while on the VW TDI the camshaft rides on "finger followers" which are mirror-smooth caps that press on the valve stem. The caps themselves can rotate (no idea if they do) and that could allow the valves to rotate underneath. But with a flat surface of the rocker pressing on the flat top of the stem... There would be very little rotational force applied there. As far as valve seals - there ARE some sort of silicone-rubber oil seals that are pressed into the head and have a spring seal around the top, but I have not been advised that these need to be replaced. I have asked at the cylinder head specialist I have been working with, and he said that unless there is a compelling reason, why mess with them, they are only keeping the light oil flow in the valve contact area of the valve guide. Having them pressed into the head is annoying though, it means they aren't coming out without being destroyed and possibly causing other damage. There should not be any wear on the side of the valve stem, that would indicate a problem. All of the valves I have seen so far have had only the lightest hint of change in the chrome that rides inside the valve guide, nothing even measurable with a micrometer (at least anything that I have available to me) so I would not worry about that. |
|
| Author: | rankom [ Sat Dec 24, 2016 6:51 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
well question … did the valves rotate or not, like most engines ? VM won't tell us , so we can just guess because there is no valve cover that we can remove and watch while the engine is running , my guess is they don't rotate properly , because hydraulic lifter keeps them tight no valve lash , if this was an old design with caps like FIAT had in there engines with caps and shims (different tickles) so we where able to adjust valve lash and let exhaust valve (RUN COOLER ) with installing tuner shim increasing clearance I'm sure they would rotate much better |
|
| Author: | geordi [ Sat Dec 24, 2016 6:59 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
Ok, but to what end though? Why would they need to rotate? Their primary movement is up and down, opening and closing. Why would they need to rotate? This also supposes that the spring tension on them is not significant and they have sufficient slack that would enable rotation. The spring tension however is quite strong, and since the caps "lock in" to the stem with strong three-groove clips, that rotation would have to be against the friction of the spring itself. Thinking about this - ALL valves are retained the same way. What says that ANY valve itself rotates at all? Yes the CAP might rotate, but I doubt that the stems themselves rotate while being held by such strong spring forces. Genuinely curious about this. Why would valves need to rotate, and what suggests that other engines do have rotating valves? |
|
| Author: | rankom [ Sat Dec 24, 2016 7:27 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
in my opinion ,,,,, i think reason valve must rotate in there seats is to achieve 100% contact with there seats , also to clean excess carbon build up ,,, and to rotate freely in there guides , if they not they will go up and down in the same spot over and over and possibly break from binding in there guides ??? this is just one of my old school guess so don't take it to seriously LOL |
|
| Author: | flash7210 [ Sat Dec 24, 2016 7:44 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
For a valve to rotate, it must have rotator valve spring retainers. I have never seen rotators on any overhead cam engine. I have never seen rotators on any automotive engine in the last 30 years. They may be common on CAT and DetroitDiesel engines but I havent seen them on any Duramax engine. 
|
|
| Author: | TURBO-DIESEL-FREAK [ Sat Dec 24, 2016 8:01 pm ] |
| Post subject: | Re: Valve failure research thread - We need your data! |
geordi wrote: Ok, but to what end though? Why would they need to rotate? Their primary movement is up and down, opening and closing. Why would they need to rotate? This also supposes that the spring tension on them is not significant and they have sufficient slack that would enable rotation. The spring tension however is quite strong, and since the caps "lock in" to the stem with strong three-groove clips, that rotation would have to be against the friction of the spring itself. Thinking about this - ALL valves are retained the same way. What says that ANY valve itself rotates at all? Yes the CAP might rotate, but I doubt that the stems themselves rotate while being held by such strong spring forces. Genuinely curious about this. Why would valves need to rotate, and what suggests that other engines do have rotating valves? If you were ANY kind of a vehicle technician you would know the reasons why valves must rotate, geordi. |
|
| Page 2 of 10 | All times are UTC - 5 hours [ DST ] |
| Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group http://www.phpbb.com/ |
|