Running HOT under load!

[Stray Cat]

Ever since I put the Banks Turbo and 700R4 trans in my '83 4WD 3/4T 6.2L Suburban, the coolant runs hot under load. I have had the heads replaced, put in a High Efficiency radiator, High-flow 7-blade flex fan, dual 14" electric puller fans, high-flow water pump, high-flow 180 degree thermostat. All of that made it much better, but on a long grade, it will overheat if I let it. The engine oil and transmission stay relatively cool, but the coolant will quickly increase. To stop it, I downshift and let off the accelerator. The overheating doesn't come with high EGTs, but with load on the engine. I can run 900-1,000 EGTs on level ground with no heating problem; when the engine is loadad on a grade, I have keep the EGTs at less than 700 (by downshifting & backing off accelerator) and the coolant climbs quickly. Once the load is removed (crested the grade), the coolant temp drops off quickly. The EGT will never go above 1,050, and boost max's at about 8psi. Does anyone have any solutions? I bought the Banks & 700R4 so I could travel from So. Cal. to Eastern AZ regularly. I have all the power, but can't use it because of the overheating problem! HELP!!! :confused:

[laidback383]

i could be looking at this wrong but maybe its your exaust how big is it single or duales please forgive my spelling good luck

[Stray Cat]

Single....three inch that came with the Banks system.

[MTTwister]

How long ago did you install the Thermostats? I recall an article describing how the rubber liner around some thermostats would work loose and restrict the water flow. Shot in the dark ..?

[tloomis]

Stray Cat, I posted a response on the 6.5TD forum. My question to you is when you did the cooling modes did you go to the dual thermostat configuration? If you didn't this is most likely your problem.

[laidback383]

maybe mine is a little over kill but i run duale 2.50 on my truck and my buddy has put on a lot of 5" single systems and he realy think its the way to go i think my self that the turbo need more of a outlet my othe thought was what gear are you running maybe with overdrive its to much of a drop and is over working the motor like i said im new to a lot of this but i have built a lot of gas motors

[Stray Cat]

Thanks for all the great responses! I have tried pretty much all of them previously. I believe that I have figured out the problem. I believe that, the high-volume water-pump I installed when I added the Turbo, was actually for a engine with serpentine drive (which turns the opposite direction). So, it is pumping the wrong direction. I have ordered the Penninsular dual thermostat system with high volume pump that definitely pumps the right direction! I will let you all know, after I get it installed, if that did it! Thanks again!

[Stray Cat]

The Penninsular dual-thermostat kit didn't make a difference! The waterpump was correct after all. My next effort will be to put the original cooling manifold from the front of the engine, on the back and tee the radiator hose. I will put 180-degree thermo in the rear manifold, and a 180 and 195 degree thermo in the dual unit at the front. Any other ideas or thoughts? Thanks!

[john8662]

Bummer on the cooling problem, even with the Penn diesel cooling upgrade. Thats a lot of work installing all that too! OK, with a load, what do you mean, are you pulling a trailor? How fast are you going when you see the overheating and at what RPM? The idea about putting two crossovers on the same engine isn't going to solve the problem, it could make matters worse, reverting the flow of coolant.

Things to ponder:

Is your temp gauge really accurate? I would install a secondary cheap one just temporarily just to try.

The thermostats are always suspect. I don't run ANYTHING but Robertshaw extreme duty stats in my 6.2's and the 6.5TD (which has the dual stats like your 6.2 does now).

The High Efficientcy radiator, how many core? I have seen some "upgrades" sold on the internet that were two cores but bigger tubes. I am a little worried about those. I personally like the factory radiators, and wouldn't run anything but.

[Stray Cat]

John, Thanks for the reply. What I mean by "under load" is a steep grade, a trailer, etc. Speed varies based on circumstances. I usually begin at about 65-70 MPH and slowly drop off as I ease off the accelerator to keep from getting too hot. Gets hot at about 2000 RPMs; the temp stabilizes or drops if I dowmshift and get the RPMs up between 2500-3000. Temp gauge is accurate. Thermostats are good; I have tried changing them several times and with different temps; I have also tested them in a jar of hot water with a thermometer. The radiator is four core and triple pass; it made a noticeable difference in temp, but still hot under load! Any ideas or suggestions are appreciated!

[POINTERMAN]

Hello , I just finished putting banks on my 6.2 but have not put under load with my trailer , but so far egt will not go over 400 and I have alot more power than I used to ,I am going to turn the pump up and try the trailer this weekend .

[Stray Cat]

Pointerman...you're just down the road from me...I am in Corona! I met another Diesel enthusiast here in Corona on this site. In fact, I am going to help him put an engine on the dyno to begin a build. Let me know what you see with the load on your truck. Thanks!

[POINTERMAN]

I know what some guys say about the banks but I just want a little help up the grade when I pull my trailer,I put new injectors ,timing chain, had the heads gone thru and I was pleasently supprised at the difference so far .I haven'tdone any cooling mods so that will be the test after I turn the fuel up and check the timing ,to pull the cajon pass . Stray Cat I would be interested in checking your project out . you can email me at pointerm at msn dot com cab 4whl

[Stray Cat]

I installed a by-pass from the back of the block to the heater, to the Radiator. To offset the by-pass, I plugged the outlet from the water-pump. So, the water going through the heater to the Radaitor is not an additional by-pass, just coming from the rear of the block instead of the water-pump. This was the brain-child of "Salemone" from this Page...thanks "Salemone"! I also replaced one of the two 195 degree thermostats in the Penninsular kit with a 180 degree thermostat so the thermostats are staggered. The first opens at 180, if the temp goes up to 195, the second opens. These mods make a big difference in initial tests. The real test will be when I pull a trailer over 600 miles from So. Cal. to East. AZ this coming weekend. I'll update when I get back the following week!

[Stray Cat]

Well, good news and bad news. The engine runs MUCH cooler with the by-pass! The grades that I had to slow to 30MPH to avoid over-heating on, and sometimes still overheated, I took easily at 55-65MPH without overheating, and with a heavier load! But, I still put on heat QUICKLY under certain circumstances. It seems to be tied to the boost level. I can be going 65MPH up a long grade at 1050 EGT, 100 degree outside temp, and maintain 200 degrees of engine temp if boost is at 4PSI or less. As soom as I get above 4 PSI of boost, the engine temp begins to climb quickly. For example, driving on level ground, 80 degree outside temp, 700 EGT, with greater than 4 PSI of boost, the temp climbs to 220 of engine temp in a minute or so! Also, there is a distinct change in engine sound and vibration at that point. At up to 4PSI boost, the engine is smooth and humming; as soon as I pass 4PSI (the slightest change in accelerator pressure), the engine growls and you can feel the vibration through the pedal and frame. So, it seems that it still puts on heat when under load, but I have narrowed the symptom. Any ideas are more than welcome...Please!

[britannic]

In what gear and rpm do you get the symptoms?

[Stray Cat]

Any gear....it has happened in 3rd gear, 4th gear locked or un-locked (TH700R4 trans).

[Ratau]

Excessive exhaust backpressure could be produced when you get boost that could generate lots off heat very fast.

Did anyone reported exhaust pressure tests done in the past?

If you got a spare hole in the manifold just before the turbine housing connect a pressure gauge via a metal pipe to it.

You report EGT within limits so just for the test pull the EGT thermocouple and connect the pressure gauge to that hole and then do the test on a turbo truck that don

[britannic]

What injector pump timing are you using Stray Cat?

[Stray Cat]

Brittanic, I don't know the timing as I haven't checked it with a timing light. But, I believe that it is a bit advanced. When I got it back from the shop that replaced the heads and fuel pump/distributor, the timing mark was aligned per factory, but it was LOUD and ROUGH and started HARD! Using the service books estimate of 2 degrees per line width, I have retarded the timing about 4 degrees. It now starts easily and runs smoothly in Southern California (800 ft); but, starts VERY hard in Arizona (6,500 ft). The glow plugs test good with a meter. I plan to try retarding more; do you have a suggestion as to how much? I don't understand why, with the new pump/distributor set to factory, it runs SO differently than before? Ideas? Could the timing chain have been put on a link off? Can the distributor be improperly installed? Any help from anyone is appreciated!!! Thanks in advance!

[britannic]

With the MHI TE06H turbo I had on my truck, I set the timing at 2.6* BTDC for the best combination of smoke, power and lowered EGTs. Each setup is different, but somewhere between 1-4* advanced at 1300-1400rpm should be about right. Hook up with a member who has a timing meter and save yourself the guesswork.

[Stray Cat]

Thanks Brittanic! I posted a request on the Member's Forum...is there a better way to find someone with a Timing Light?

[Peter J. Bierman]

What about the fan?
Does the fan clutch kick in at those high temps?
I have heard not much good about the flex fans on diesels.
At temps as high as 220/230 you should hear the fan roar.
I did not read you replaced the clutch, might be an option.
Remove the electrics, if they don't solve the problem, they are just in the way off the airflow.
You can also try a T-stat combo off 160 /180 to lower the point off circulating through the radiator and get a bit more margin.

What does the exhaust smoke tell you?
Over fueling ( lots off black smoke ) will heat up the engine quickly but you should see high EGT too.

Is there any upstrucktion in front off the radiator, like a bug screen, fancy bullbar or A/C condensor with bended fins?

I am thinking this way couse the temps react to mods you made but not solve it.
So it looks like a heat rejection problem.

Keep us posted,

Peter

[Stray Cat]

I borrowed a diesel timing kit from another local member. My timing was at about 6.5* ATDC @1300 RPMs. I tried going to 3.5* ATDC @1300 RPMs and it got louder, EGTs increased slightly, and it had less power. I split the difference at 5* ATDC and it is smooth, quiet, and powerful. I think that I found the sweet spot for timing on my engine. I haven't tested the heat under load problem since.

[Stray Cat]

I borrowed a diesel timing kit from another local member. My timing was at about 6.5* ATDC @1300 RPMs. I tried going to 3.5* ATDC @1300 RPMs and it got louder, EGTs increased slightly, and it had less power. I split the difference at 5* ATDC and it is smooth, quiet, and powerful. I think that I found the sweet spot for timing on my engine. I haven't tested the heat under load problem since.

[Stray Cat]

I borrowed a diesel timing kit from another local member. My timing was at about 6.5* ATDC @1300 RPMs. I tried going to 3.5* ATDC @1300 RPMs and it got louder, EGTs increased slightly, and it had less power. I split the difference at 5* ATDC and it is smooth, quiet, and powerful. I think that I found the sweet spot for timing on my engine. I haven't tested the heat under load problem since.

[doncannon]

Stray Cat,

I had a problem with overheating and someone suggested to me that it could be the thermostat and I said I just replaced it. They said look at the opening in it, if it is like a gasser it is too small and suggested one from kennedy diesel with a much bigger opening (180 degree). This made a difference for me, however I just have the old single stat.

Pointerman,

When you do turn up the fuel I would only go 1/4 turn. I went 1/4 more than this (1/2 turn total) and seems to get high egt. Should have stuck to DP members suggestions. I have turned it back now seems better.
Hope this helps guys,
Don

[Stray Cat]

:mad: DAMN!!! :mad: Driving smoothly down the freeway today and the engine seized. I got it towed home, pulled the oil pan, and found that the bottom of the #4 piston disintegrated. A portion of the bottom of the #3 cylinder was broken off, a piece was shot through the side of the oil pan, and there are hundreds of pieces, varying in size, in the oil pan. It looks like I need a short block. :mad: DAMN!!! :mad:

[john8662]

whoa! Any idea what went first? been any knocking before hand? Did it break the crank?

[Stray Cat]

It started knocking about a week and a half before it froze. I think the #4 piston went first. I still have to take the heads off to inspect the top-end.