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Serious EGT problem? And need overflow tank in Lubbock ASAP

J

JeffMD

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Hey y'all, this is Jeff's brother-in-law Kevin.

Jeff & family are having some serious problems on a road trip. Truck info is in his sig - BUT - he recently added an A-Team Turbo and removed his intercooler :skep:, but hasn't updated the sig yet. Truck has 4.10 gears and 265/16 tires. 94 Suburban K2500.

They are pulling a 27' travel trailer. Weighs 4600lb empty; it's a rental and only loaded with what the family needs for 10 days, so it shouldn't be too heavy. This is the biggest thing he's pulled with this truck. Truck is carrying 2 adults, 2 kids, and the usual crap.

Problem 1: On flat ground, 54mph, 4lb boost, his POST-turbo EGTs are reading 1150! Coolant temps were OK. Blowing slight black smoke on moderate hills. Weather Channel says current temp is 111! :eek:

My diesel truck has a Brand "C" engine :cool: , so I'm no expert on the 6.5, but this seems like it shouldn't be happening. Could his EGT really be that high? If so, is there something he can adjust while on the road to help it? Would changing back to a stock chip help? I'm hoping his gauge has gone crazy.

Problem 2: his radiator overflow tank sprung a leak this afternoon and he has to stop frequently to add water. Water temps are now hitting 210 before he refills. He will stop in Lubbock and hope that Scoggin Dickey has the part tomorrow. If not, does anyone local have a spare or a recommended source? Is this failed tank just something that happens, or could it be caused by some other underlying problem?

I'll be checking replies here regularly and passing along any info you can offer. If any Lubbock folks can give some personal help, please call me at 941 - six eight five - 7504. If you're between Lubbock & the Grand Canyon (or on the return route via San Antonio to Houston) and might be able to help with future issues, please LMK too.

thanks!!
kevin
 
While it's almost impossible to tell without seeing the vehicle, that does sound like a buggered thermocouple if it happened all at once with no other changes.

What were his non-towing temps like?

If this just started when he started pulling, it very well could be egt's.

But that would also be somewhere around 1250-1450.

That is waaaaayyy high for a 6.5, if it's accurate.

If he can't figure out what it is, I'd drive the egt's (ie: back out of the throttle) until he can figure it out.

What kind of program is on the Heath Prom?

IE: performance, towing, etc.....

He should be able to just pull out the adapter and reinstall the stock "blue" chip if he wants. Unless Heath desolders the EPROM and puts in a new one. I don't really know, I've never seen the inside of an OBDI heath PCM.....
 
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I had this exact same scenario happen with my ATT and Banks stinger exhaust. Rip off that crappy exhaust system and the ATT will be able to spool alright to fix the problem. If it has a Catalytic converter rip it off immediately.

Sounds like his timing may be too advanced as well, and going back to the stock chip could help, as they are retarded at sustained fuel rates. More boost would help, but the ATT is not wastegated. Somehow he is burning a lot of fuel to get high EGTs but not getting turbo drive pressure. This is likely because its too advanced with too much fuel and its spitting fuel out thats still burning. Free flowing 4" exhaust goes a long way to solving this.

This is mainly because the IATs are high too. One of the reasons people need revised tuning with the ATT is that a chip can be programmed to ouptut a lot of fuel early where the GMx would be able to spooling to 9psi boost.
 
Gauge has been intermittently bouncy, so hoping these high temp readings are a failure mode. It's an Autometer. He'll try to get a new thermocouple tomorrow too.

Typical readings recently, non-towing:
200-300 at idle
400 at cruise
600 when hot-dogging

He patched the overflow tank with Liquid Steel and it seems to be holding, so that's good...

thanks!
kevin
 
JeffMD said:
Gauge has been intermittently bouncy, so hoping these high temp readings are a failure mode. It's an Autometer. He'll try to get a new thermocouple tomorrow too.

Typical readings recently, non-towing:
200-300 at idle
400 at cruise
600 when hot-dogging

He patched the overflow tank with Liquid Steel and it seems to be holding, so that's good...

thanks!
kevin
Click to expand...

If the gauge has been intermittent or swinging, it's worth his while to check out the connections.

All a thermocouple does is produce voltage and the gauge reads it and displays it as temperature vice voltage.

I cant remember, but I think autometer had some funky kind of connector on the end of the thermocouple lead which can cause problems.

check it out for corrosion or bad contacts.

A pyrometer is also a very sensitive piece of equipment since it has to read very small voltages. They are very sensitive to problems with ground connections at the gauge. Check those out too...
 
Have him change out the exhaust system ASAP, I had same post turbo temps and low boost with ATT and Banks Stinger exhaust system. 4" system totally resolved the issue.

Although I could leave smokescreens miles and miles long going up long mountains. Have him downshift to third and slow down to RPMs more like 2500+ rpm to drop the EGTs until changeout of the exhaust.
 
Thanks, Buddy! The stock chip is here, but if necessary I can FedEx it to him.

Is the thermocouple an Autometer-only item, or can it be sourced more easily?

Edit: Y'all type fast! :cool:

Definitely only has light smoke, so I'm hoping it's the thermocouple, not an actual EGT problem. He's checking the connections and I'll see if I can locate a new one in Lubbock. Previously, the gauge sometimes didn't work at all, sometimes bounced, but when it worked it appeared accurate. If the new readings are accurate, he's risking serious damage, as well has having a really LONG, SLOW, drive!
 
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When I pulled my trailer to Jacksonville, Texas on the 10 - 12 June 2011 the small hills of East Texas was kicking my trucks ass.

My truck weights in at 6,600 lbs. with a full tank and me in it. My trailer is suppose to be maxed out at 6,452 lbs. I had my wife, two kids, two dogs, and all the camping gear we needed and then some. I am willing to bet I was exceeding 12,000 lbs.

At first I was trying to keep steady at 65 MPH. When I got to the other side of Palestine, TX is when the steeper and more frequent hills started to hit me.

My trucks temperature gauge regularly sits between the second and third line starting at the 100 mark. Towing on flat ground it stayed in the same exact spot. On small hills with a break after it would move up one line, sometimes. After Palestine it moved up to one mark below 210.

When I noticed this I slowed down to between 55 and 60 mph. It almost immediately dropped back down to the normal mark on my truck.

When you push these trucks hard they start getting hot. At least from my one experience. The other place I go camping is less than a 30 minute drive. So I really do not watch my gauges like a hawk. Unlike the 3 plus hour trip to Jacksonville.

What I am trying to say is slow down. It is suppose to be a vacation, enjoy it! :thumbsup:
 
Well I was leaving smoke screens going up the rocky mountains at 65mph, I had to slow to 50mph in 3rd gear in the truck lane to get the EGTs down. I have 3.42 gears, and I wasnt even pulling anything, but could only make 4-5psi boost. Once I changed out the exhaust (which I also had a cat) the boost on the same mountains was more like 9psi and EGTs only around 800F preturbo, since I moved it from post to pre with the exhaust change.
 
The problem with the Autometer is most likely that is was not installed correctly. The Pyro MUST be grounded TO THE ENGINE or it will do all kinds of bouncing around.If for some reason he does have it grounded to the engine then follow the yellow wires and most likley they burned on the exhaust or got cut on something. The overflow tank is not pressurized on a 94(It shouldn't be anyway) so in reality he could almost run without it or use one from anything. It could run without it but the coolant level would have to be a little low in the rad. As far as the high egts, those are some serious temps. The obd1 prom can just be unplugged and the old one plugged back in. Heath tunes run high egts. That much I can say from experience.
 
Acesneights1 said:
The problem with the Autometer is most likely that is was not installed correctly. The Pyro MUST be grounded TO THE ENGINE or it will do all kinds of bouncing around.If for some reason he does have it grounded to the engine then follow the yellow wires and most likley they burned on the exhaust or got cut on something. The overflow tank is not pressurized on a 94(It shouldn't be anyway) so in reality he could almost run without it or use one from anything. It could run without it but the coolant level would have to be a little low in the rad. As far as the high egts, those are some serious temps. The obd1 prom can just be unplugged and the old one plugged back in. Heath tunes run high egts. That much I can say from experience.
Click to expand...

94 the tank is pressurized. It's the surge tank style. At least the 94 i did the top end rebuild on was. The old style(which i prefer) seems to have died with the mech injection 6.5s in 93.
 
As far as the OP, now looking at that pic I remember I had to replace it and GM had it in stock. Try the dealer. it was not that bad IIRC.
 
My 94 Suburban is pressurized. The radiator cap sits on top the overflow/surge tank on the firewall.

Geez Aces.... you posted twice while I was writing the two sentences above. :WTF:
 
My (1994) coolant tank was pressurized, too.

I agree with everything Kenny and BJ said here about the pyro, Kevin... have Jeff check the pyrometer ground, make sure it is right back to the engine ... (any RF noise in the alt will make it bounce - at least that's what my old one did) and check the wiring for nicks or scrapes.

Buddy is right on with the exhaust problem, and I'd like to know if Jeff changed the crossover when he did the exhaust? The 94 x-over sucked. REAL bad. It was anough of a problem with a wastegated turbo, and an ATT needs flow even more than a GM4

Finally, ask him if he still has the flat-panel airfilter, if he did the (fender) snorkle mod, and have him check the condition of his airfilter. Having your turbo run good means both getting exhaust OUT and getting air IN.

And in the meantime, follow Marty's advice. When in doubt, slow down, don't work it so hard.
 
Wow, thanks for all the great responses! There are a bunch of diesel performance shops in Lubbock, plus a Chevy dealer with a great reputation, so hopefully whatever he needs, he can get it there in the morning. I'm sure he'll thoroughly inspect the pyro wiring as soon as the sun is up!


Thanks again!

kevin
 
quick notes b4 I lose my laptop power (at campground) Did 2.25 cross over Thursday at local muffler shop. They said the old definitely was restricted. Aftermarket big honkin gauze type conical filter.
 
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