Engine/Transmission (1994 - 1998) 12 valve low on power high on egt?

[DonFitzwater]

I'm looking at a friends 6bta5. 9 m3 marine 12 valve. It's a factory 370 horse. It takes forever to spool up to 25 psi (spec) and blackstacks the entire time... ..... egts are running 1300 under full power. The injector pump has been sent out, came back ok and was installed. The shop that did the install put the pump to tdc and the engine to tdc but didn't actually set the timing? The data tag says 24 degrees..... am I missing something? This engine white smokes at idle until up to operating temp and is hard to start. I have thought about it somewhat and believe we have a timing issue and possibly an afc problem... ... ... ... ... . Injectors are all new... ... ... ... fuel pressure from the lift pump is at spec... ... ... ... ... ... ... ..... The turbo seem to be in good shape... ... ..... Joe G..... are you listening? What do ya'll think? I also need some good timing instructions from somebody... . I've got a timing kit from Snap-on so I just need some decent instructions. Thanks!

 

[bmoeller]

Replace the air filter(s)? Or check the exhaust for a restriction.

 

[DonFitzwater]

The air filter is new and the exhaust is wide open and its only four feet long.

 

[Forrest Nearing]

make an agressive search for boost leaks!



and I would verify/adjust timing with a dial indicator or spill port method. I would bet that even if you find/fix boost leak, your timing is probably off as well

 

[DonFitzwater]

The timing will be checked this afternoon and as for a boost leak, nothing has shown up under full power runs with the soap and water trick on all of the intake stuff associated with this engine. It does have a big liquid cooled intercooler and I'm not sure that it has been pressure checked... ... ..... it's not losing any water... ... ... the inside of the compressor is nasty black and I don't recall my old truck looking like that? I was thinking this is a timing related issue (slipped timing) and maybe an afc problem? The big issue is we cant run this boat because it's 50' long and were 450 miles from the Valdez! I can fire it up but only at idle

 

[KingS]

the inside of the compressor housing is black any moisture in it as well sound like the turbo seals might be shot just a though but check timing first.

 

[DonFitzwater]

Timing is being checked right now and he'll call me when its done to let me know what's up. Were checking on a Semi to see if we can launch it in a large gravel pit here in Fairbanks so we can run it up under a load. I'll post as soon as I hear about what the timing was set at.

 

[GOlsen]

I don't want to hijack the thread, but... How do you check for a boost leak? I work with compressed air systems, so I'm familiar with using soapy water, but... without the truck under load, does the turbo create enough boost to do it this way? If not, what's the easiest and safest way to check? Thanks.

 

[DonFitzwater]

When looking for a boost leak, I've always isolated each component and tested like that... ... ... Plug the intercooler and pressure it up, It would be easy to soap and water this boat engine if I could just get it in the water!

 

[EHarvey]

Not sure about this , but would a bad injector leaking in to cylinder cause this problem . Just a thought.

 

[DonFitzwater]

We put in a set just in case, no go.

 

[RON'S RAM]

I don't want to hijack the thread, but... How do you check for a boost leak? I work with compressed air systems, so I'm familiar with using soapy water, but... without the truck under load, does the turbo create enough boost to do it this way? If not, what's the easiest and safest way to check? Thanks.

Check out this link to see a picture of a boost leak tool that Signal73 made. Works good and is simple to make.

https://www.turbodieselregister.com/forums/truck-911-archive-members-only/179839-loss-power.html

 

[GOlsen]

Check out this link to see a picture of a boost leak tool that Signal73 made. Works good and is simple to make.
https://www.turbodieselregister.com/forums/truck-911-archive-members-only/179839-loss-power.html

That's some great info. Thanks, Ron! I'll have to assemble one of those this weekend and give it a shot.

Dave

 

[DonFitzwater]

Just an update. The fuel pressure under load dropped off early, put a lift pump on and nothing changed... ... replaced the overflow valve and bingo, problem solved. She gets up and goes now with normal egts and no more smoke. Thanks guys.

 

[Forrest Nearing]

thanks for the update! always interested to hear the cause/cure!

 

[Bart]

make an agressive search for boost leaks!



and I would verify/adjust timing with a dial indicator or spill port method. I would bet that even if you find/fix boost leak, your timing is probably off as well

Forrest has it RIGHT!!!! He said the same thing to me, except he left off the word AGGRESSIVE! I had high egts and a max of 25 psi boost with a 62/14 cm tubo. To cut to the chase, I had a polyurethane puck made. It was 3" in diameter and about 2" think. I installed it in the rubber boot(hose) just off the turbo. CAREFULLY applying compressed air through a painter's inline regulator to a quick air line nipple that is screwed into the puck until I hit 20 psi. ANY air leaks will be come VERY event. I found three. Two ruptures of the top of the intake cover plate gasket and one for the plastic boost gauge hose. Now my 25 psi will peg the gauge at 35+ Now, truck performance can be down right scaryOo.

 

[12V Ford]

When you do a pressure test where you hook the air up to the intake of the turbo, do you unhook and plug the intake or just run it into the motor????



If your turbo seals are bad, will air leak into the oil line or exhaust???



My truck has all of a sudden developed a slow spooling, high egt issue without changing anything. My stock turbo has about 205k miles and I'm wondering if it is going bad. My Fuel pressure is also running low, but I would think high egts are not from low fuel pressure.

 

[DonFitzwater]

With this boat issue, we found that the turbo would not spool aggressively or fast enough to keep up. Egt's would climb but boost would not. Start with the simple stuff and check all the easy things first... ... fuel pressure, air leaks, fuel filters etc.