6.5 over boosting?

[Veg_Out]

Craig,

If you haven't cleaned out the radiator fins and the entire area between the radiator and the condensor/oil coolers, you are in the fastlane to destruction.

These motors are very strong, very stout and very prone to explode when hot and or overboosted with the stock GM turbo.

Let my broken to pieces motor be a warning to you! I hope you never have to build a new one!

Good luck!

 

[craig12]

Craig,

If you haven't cleaned out the radiator fins and the entire area between the radiator and the condensor/oil coolers, you are in the fastlane to destruction.

These motors are very strong, very stout and very prone to explode when hot and or overboosted with the stock GM turbo.

Let my broken to pieces motor be a warning to you! I hope you never have to build a new one!

Good luck!

i dont think theres a cooling problem, its all clean under there i made sure of that. i can go long grades towing and it doesnt even come close to 100 C on the gauge

 

[gnel]

For sure someone's been in there and has at least messed with the stock system a bit. The VAC hoses have been replaced. Might have been simple maintenance for "cracked from age" stockers.

Since the hoses have been replaced, it's possible they're backwards on the wastegate solenoid (thing with teh blue wire connector). The wastage vacuum hose should be on the rear most nipple of the solenoid.

My 98 will peak somewhere around 10-12 psi (not really looking at the gauge at that point) with the throttle mashed and accelerating hard.

15 psi sure sounds a tad high.

Where's Sooke? You on the mainland?

I'm on the island.

If the hoses are reversed at the solenoid what happens? No vacuum? To much vacuum? I don´t mean to be jacking this thread I´m just curious.

 

[craig12]

i made a homemade turbomaster, and it seems to boost more relative to the fuel im giving it, before even 1/4-1/2 throttle went to 15 psi +, now with the mechanical wastegate i adjusted, it hits between 9-10psi max boost, and exhuast pushes some black not a crazy amount almost totally clears up up after a second or two of full throttle. looked alil closer at my PMD and it seems like it doesnt even have a resistor installed, thinking of getting stock number 1 resistor in there. full trottle EGTs hit 800-900 F with the guage sensing it after turbo few inches past it on the down pipe. Not sure if this is good or not, since it could be way higher in the manifold before turbo, i think i should relocate it. so far the mechanical waste gate solved most my problems as long as the previous owners didnt bump the fuel up some exotic way, all i can really do on my own is put a stock resistor in there and hope for the best, try towing it like this.

 

[WarWagon]

#1 or #9 resistor is not your problem. (Missing is a problem, but 1 or 9 will not change things enough to matter.)
The computer that controls the fuel and attempts to control the boost is. The Heath Turbomaster guide says to set the boost max of 5-7 PSI with the factory program, and this is with the trailer load high gear or high RPM. Over 7 PSI the computer cuts fuel until the ignition is turned off. Unless you have it programmed.

Possible the turbo wastegate is sticking open or closed. Now you have a homemade turbo master... You need to know if the computer is programmed or not. Reflash it if in doubt. This would be at the GM dealer or ordering a flash from say Heath diesel etc. You have to know what you have in the computer.

Wanting to tow without fixing your problem with cooling, black smoke, and boost... Well let me suggest a military surplus 6.2 repower project when the above problems blow up your engine. I got the blown up engine t-shirt for that BS overheating towing already. Hope for the best is getting a rebuilt not worn out engine to drop back in after it lets go...

Steady black smoke is a problem and you should not tow with that going on. A light haze is ok. The turbo has to spool up to full boost and black smoke can happen while it does so. So a short time of black smoke after you stomp it is ok as long as it clears up quickly.

Also check the simple stuff like a restricted air filter, failed crossover exhaust pipe and get the restrictive undersized factory replaced if it is still on there. Kitty being plugged is also a possible problem for overheating and smoke.

 

[craig12]

i can adjust my TM so it doesnt push any black full throttle makes more like 10 psi though, just changed dirty air cleaner to new k&n and change the fuel filter yesterday. at the moment it sounds like getting the computer reflashed is my best bet thanks.

i do have an egt guage, its rather crappy but, it gives me a rough idea on how hot its getting believe me id pull over way before id ever put the motor in danger...

 

[WarWagon]

Does it cut power at 10 PSI? You are good till 14 PSI on the turbo with an aftermarket tune. (So if it isn't cutting power you are tuned. Who knows with what though.)

Keep an eye on the K&N: they tend to plug up quickly. Why I don't know because they let a lot of dirt through them vs. a paper filter. Return it if you still can get your money back on it... First thing on my truck I did when I got it used was remove the dirt filled to the top of the pleats K&N and throw it away...

 

[craig12]

no power cut but, before when it hit 15 psi+ it wasnt giving anymore power and it was hitting it at like 1/4 trottle, it was like useless boost, like just blowing hot air. it was defueling i suspect, i have never seen my truck push any black (expect cold start) till i put my homemade wastegate on, now it pushes black like my buddies totaly stock 92 6.5 tb. There was something wrong with the vacuum controlled waste gate, just a junk system anyways, why else would it cause the computer to totally open the waste gate while im towing, overboosting by a mile.