Engine/Transmission (1994 - 1998) Major EGT issues

[AH64ID]

They come factory preset at 42-45psi. I haven't touched the waste gate on this turbo and it is only about 4000mi old

It may be set that high, but the 62mm maps I have seen show it as a 3. 5:1, which at sea level is about 37 psi, and 30 psi at 5K feet.

 

[JMcCoy]

In my opinion, it sounds like you have a problem not directly related to your modifications. Although I'm sure they don't help. Often people (myself included) overlook the basics and start digging too deep. I'm going to spitball a little here. Do you have an exhaust brake? If so, it may be hanging up and not fully opening. I assume you have a new thermostat. Maybe you received a bad one. You mentioned your air box pulling air from the fender. Is that the only place it pulls from? The hole in the fender is pretty small. Since your air requirement is so high, you may need more flow. I too have an ATS exhaust manifold. The casting was horrible. I spent hours porting it out. It had large pockets covered by casting garbage. I had to remove large amounts of material to make it right. I don't hear too many complain about this so I figured it was a rare incident. If you have the same manifold issue I did, it would definately cause problems. Is your fan clutch still working properly? Is you water pump operating properly? A pump can fail without leaking. I when to auto zone to purchase a pump. It was very poor quality compaired to the oem pump. The casting was rough and the welds were burnt. I then went to the dealership. Hope this helps. Good luck.

 

[LVJUNIOR]

In my opinion, it sounds like you have a problem not directly related to your modifications. Although I'm sure they don't help. Often people (myself included) overlook the basics and start digging too deep. I'm going to spitball a little here. Do you have an exhaust brake? If so, it may be hanging up and not fully opening. I assume you have a new thermostat. Maybe you received a bad one. You mentioned your air box pulling air from the fender. Is that the only place it pulls from? The hole in the fender is pretty small. Since your air requirement is so high, you may need more flow. I too have an ATS exhaust manifold. The casting was horrible. I spent hours porting it out. It had large pockets covered by casting garbage. I had to remove large amounts of material to make it right. I don't hear too many complain about this so I figured it was a rare incident. If you have the same manifold issue I did, it would definately cause problems. Is your fan clutch still working properly? Is you water pump operating properly? A pump can fail without leaking. I when to auto zone to purchase a pump. It was very poor quality compaired to the oem pump. The casting was rough and the welds were burnt. I then went to the dealership. Hope this helps. Good luck.

I don't have an exhaust brake (but I wish I did). The thermostat was reaced with no change. I can watch the temperature gage and see the thermostat kick in. The water pump was replaced with a cummins pump she. The Motor was rebuilt 6k ago. I have the AFE stage II air filter and box. It is not a tight fit to the fender but close. The last one was an open top box. I looked at the manifold when I put it on and it looked good to me. Could have used a 1/16th here and there. It nothing major. Where were your bad castings? Were they at the ports or deeper on the manifold. I can hear the fan sound like a B52 bomber at times and when I spin the fan it has decent resistance. Is there another way to check.

To me the water temp issues seem to be a result of heat soak. The temps stay steady for the most part until I run at 1150 or above for a long period of time. In my opinion if I can lower my EGTs my cooling system would be able to keep up. My truck runs 1050 on the flats and trailer weight doesn't seem to have a dramatic effect on EGTs

 

[cerberusiam]

My truck runs 1050 on the flats and trailer weight doesn't seem to have a dramatic effect on EGTs

That would make me suspect the CAC is not doing as good of job as possible. Have you at any time trashed or blown a turbo? Is the CAC new?

Did you do the engine rebuild and swap or did someone else? A person I have been talking with bought a truck 6 months ago. Truck has never run right and he has just been working out the issues. It was an engine swap the PO could not get finished and make run so dumped it. The truck would start and run fine but would NOT rev about 1700 rpms, free rev or in gear. No codes, no excessive smoke, fuel pressure was good, filters good, etc, etc. In an act of desperation he started at the intake working backwards looking for problems. Voila!! Sitting on top of the grid heater was a cloth rag!!! Problem solved.

Obviously grid heaters were non-functional but it let thru enough air to start and run but not rev very far or fuel hard enough to generate tons of smoke. A rag inadvertently left in the hot side of the CAC would make a very hard to track problem.

 

[hsmith]

^^^ I agree somewhat, but that would cause boost issues also.

 

[LVJUNIOR]

I am not familiar with the term CAC but I am assuming it means charge air cooler or intercooler. The engine was removed rebuild and reinstalled by someone else but this problem existed before the rebuild as well. I have verified the intake is clear but have never looked inside the intercooler. The boost comes in very fast and hard on my truck to above 42psi which would seem to ruel out a restriction in the intake tract wouldn't it?

 

[AH64ID]

There could be a restriction that effects heat removal, but not flow and pressure.

 

[cerberusiam]

There could be a restriction that effects heat removal, but not flow and pressure.

Exactly, you could still have the same boost with 1/2 the CAC plugged but your charge air temp is gonna be way high. Since it existed before its hard to tell but I think my next step would be a CAC change. They are expensive little buggers but when they don't work correctly there is no way around the problems.

 

[JMcCoy]

I looked at the manifold when I put it on and it looked good to me. Could have used a 1/16th here and there. It nothing major. Where were your bad castings? Were they at the ports or deeper on the manifold. I can hear the fan sound like a B52 bomber at times and when I spin the fan it has decent resistance. Is there another way to check.

Sounds like you have been doing all the right things. My manifold had bad castings all over the place. Right at the face of the runner all the way to the back. I cannot imagine they are all that way. I could really tell the difference with spool up. Now that was from a stock to the "ported" ATS manifold. As far as the fan goes, I don't know exactly how to test it. I'm sure there is a way.

 

[LVJUNIOR]

checked the fuel pressure today and it was over 20 at idle and 30 or more at speed. Going to check timing on Saturday and If it is good going to pull the injectors and have them tested and also check the cam timing

 

[alliscrawler]

cerverusiam is correct you need differnet gear set, 410's for towing big loads. Big tires look cool but screw up your gearing for towing, and hey slowwwww down, people want to pull these kind of weights with an auto in OD are asking for a trip to the transmission shop, even on flat ground. OD should never be used while towing. (well okay I do use it down hill) LOL I have the exact set up you have and run the BD transmission lock and pull close to 18000 pounds total with no issues. But you have to keep your foot out of it and use the lock up and shift down when your going up a hill with a load. I tried a 15 degree hill here and noticed my transmission temp was going up over 220 plus and my egt was 1350 and cllimbing and had plenty of throttle left. Same hill in 2nd gear locked pulled hill at 185 on transmission and egt 1150. You dont see many big rigs running around up big hills at 65 either, use your gears and keep your engine and transmission alive. I have all my gauges marked for quick reference and also use a deep pan on the transmission with additonal heavy cooler with manual switch to fan, BD has a great transmission lock up that allows you to pretty much use your auto like a stick. Cant say enough about the lock up it really helps keep temps down. I think Summit Racing also has a 5 inch exhaust thats pretty reasonalbly priced, need to get the hot air out and cool air in. Not sure about the rig getting hot, did you upgrade your connections when you went with the bigger turbo? The increased turbo pressure will cause problems with the hose connections you might be loosing some of the air out of intercooler if your using the stock clamps. If you want to try propane injection it also works to keep down the egt's and is supposed to get you more power and hey were all about more power. I know some one who has a used Bully Dog propane system for sale if your interested let me know. good luck.

 

[LVJUNIOR]

No offense but if I can't pull a hill at 65 grosing 15000# there is no reason for me to own the truck. I grossed 22,000# with a stock duramax on 35's with 3. 73 gears and could go as fast as I wanted to. This truck has 4. 10's and I keep it at 2000 rpm or more when towing.

I did find a few issues with the truck that had to be corrected. The timing was set wrong. It was set for a 180hp pump instead of a 215hp pump so it ended up being 14. 5*. I reset it to 19. 5*. The injectors were supposed to have been stage 2 DDP and ended up being stage 3 which uses a 370 marine nozzle. Those nozzles are know. For being hot a d smokey. I am having another set of injectors built with the correct spray pattern. I should have it back together by the end of the week to test the changes but I am thinking it will be a big improvement

 

[NIsaacs]

No offense but if I can't pull a hill at 65 grosing 15000# there is no reason for me to own the truck. I grossed 22,000# with a stock duramax on 35's with 3. 73 gears and could go as fast as I wanted to. This truck has 4. 10's and I keep it at 2000 rpm or more when towing.



I agree, you should be able to put your foot in it with any axle ratio, in any gear. If it gets hot with 3. 55's for example, it will get hot with 4. 10's.



Nick

 

[cerberusiam]

I did find a few issues with the truck that had to be corrected. The timing was set wrong. It was set for a 180hp pump instead of a 215hp pump so it ended up being 14. 5*. I reset it to 19. 5*. The injectors were supposed to have been stage 2 DDP and ended up being stage 3 which uses a 370 marine nozzle.

Oh, that will definitely put a crimp in the driveability and readings you are seeing. That is too little timing and too much fuel for towing which tracks with your EGT's doing what they were.

Unfortunately, what you could with the DMax is not a good compariosn to the a 12V. There are too many differences in the fuel management that will preclude a solid comparison. Transmissions also make a huge difference in what happens on grades with a load. The Ally is pretty good at making that a seamless process where a 47\48RE struggles.

 

[alliscrawler]

No offence at all, your right your can put your foot in any of them. I too would be disappointed with the 15000 towing, But if you want them to last and not buy new trucks every other year, go slow and get better milliage and save yourself some big money. I think the transmission lock really helps also. I used too put my foot in it , but I guess I am just getting old. My last truck went 290,000, 3 transmissions, one of them $6500 . Ford f350 with 7. 3. Good truck but my 97 actually has more power and pulls better... off course it rides like a tank. I have too much money in mine usually only use 1/4 to 1/2 throttle to pull what I need to pull but I am an old man that has broken lots of trucks and has just gotten tired of buying and building new ones. I agree on the timming and getting different injectors, I can't really use all the power available wtih the 75hp injectors as you said they do run hot. Hope the new injectors get you where you want to be, I may try to find someone and do a swap to 45 hp ones. Just curious what year was your Duramax,

 

[LVJUNIOR]

No offence at all, your right your can put your foot in any of them. I too would be disappointed with the 15000 towing, But if you want them to last and not buy new trucks every other year, go slow and get better milliage and save yourself some big money. I think the transmission lock really helps also. I used too put my foot in it , but I guess I am just getting old. My last truck went 290,000, 3 transmissions, one of them $6500 . Ford f350 with 7. 3. Good truck but my 97 actually has more power and pulls better... off course it rides like a tank. I have too much money in mine usually only use 1/4 to 1/2 throttle to pull what I need to pull but I am an old man that has broken lots of trucks and has just gotten tired of buying and building new ones. I agree on the timming and getting different injectors, I can't really use all the power available wtih the 75hp injectors as you said they do run hot. Hope the new injectors get you where you want to be, I may try to find someone and do a swap to 45 hp ones. Just curious what year was your Duramax,

I hear what your saying about taking it easy. My last trip I kept it under 55 and still had issues I had to drop down to 35 on a 6% grade. The injectors were supposed to be 75hp but actually ended up being the 90hp version.

The duramax was a 2007. 5 first year of the particulate filter. Best truck I have ever owned but my dodge is so far from stock I just can't justify getting rid of it. The motor is the least of the upgrades. If I can get it to tow well I will love it

 

[alliscrawler]

I think your on the right track on injectors, I am considering going all the way down to 45 hp ones, my understanding is that the 5 inch exhaust is also a big help. Never owned a Chevy before but lots of folks love em, I think I stay with mr cummins its noisy and smokes and leaks fluids just like me... LOL

 

[cerberusiam]

my understanding is that the 5 inch exhaust is also a big help.

A 5" exhaust when one is trying to maximize efficiency is a huge hindrance not a help. Stock exhaust minus the muffler is way better suited to a towing rig than 5".

 

[LVJUNIOR]

I like the 12v for its simplicity. I may have high EGTs or a rough idle etc. but with some basic hand tools I can still fix it enough to limp it home which is a huge advantage for how I use my truck. I have heard mixed reviews on the 5" exhaust but the general consensus I have found is that 12v are good with a 4" up to around 800hp

 

[DWeaver]

Any updates LV?



Been keeping my fingers crossed that you found the culprit.