Engine/Transmission (1994 - 1998) 12v turbo problem and questions

[Kiohio]

Welp...
Got it apart, put a #10 plate in it, still need to tweak starwheel.
I ran out of time.
No smoke like it was before! Finally some resolution!
Take a look at the plate that was in it.
No wonder it acted unusual.
I adjusted the foot so it rides right on the edge of the bottom of the fuel plate.
May play with the old plate, the one pictured later on.
Do a bit of grinding...

KO

 

[Kiohio]

Something else I found out playing with it this morning... .

Before doing this I couldn't get more than 2750 rpms out of it.

If I locked out overdrive on a hard pull it would not rev any higher.

Now it will go to 3k.

That fuel plate was definitely holding me back at some rpms.

I also don't need to buy a 3GSK



KO

 

[Forrest Nearing]

the truck will run much stronger with a different GSK... just because the engine will rev to 3000 doesn't mean you're making power to 3000rpm

 

[CWeaver]

12V Waste Gate closed ?

Hello everyone,



I also recently purchased a 12V (96' 2500 below) this summer. It runs strong but a bit Smokey. It will build up to 42 pounds of boost if I stay on it. I was told this is BAD because the stock head can only take (or is rated for) 25 pounds of boost? Should I be worried about this?



I think my WG may be adjusted closed or rusted closed? I couldn't find a external WG door? Are they internal?

How do I check if its opening? I was told there's a allen bolt to adjust this but I didn't see one. I tried lubing the waste gate (threaded) rod and wiggling in case it was rusted, but got little movement out of it.

How do I adjust this? The truck is engine is Stock with no upgrades other than a fuel plate, air cleaner and guages, (trailer special package).

Any help appreaciated ! -thanks

 

[fest3er]

The engine, in stock form, generates less than 25# of boost at best. In stock form, the head gasket, using stock head bolts, can generally hold up to 45# of boost (or a wee bit more) before it yields. However, if the ignition timing is greatly advanced or nitrous/propane/methanol are being injected, peak cylinder pressures may be very excessive and cause premature gasket failure. Keep your foot out of it until you verify that injection timing is set sanely and you don't have nitrous/propane/meth injection.

If there is a tube from the wastegate to the intake manifold somewhere, you can pipe shop air into it. Start at 5 PSI and slowly regulate the pressure up until the WG starts opening. 25-35 PSI should be a reasonable do-not-exceed pressure.

 

[BigPapa]

It will build up to 42 pounds of boost if I stay on it.

The truck is engine is Stock with no upgrades other than a fuel plate, air cleaner and guages...

Like fest3er said, these statements don't jive.



Scott

 

[CWeaver]

I was assuming that I was building that extra boost because the previous owner had possiblly adjusted the WG shut?

I know the original owner have the dealer tweak it for "efficency" towing a goosneck motorhome.....

Again I'm not even sure I found the waste gate? Can anyone shed some light on this.

Thanks-

 

[Forrest Nearing]

they may have installed a non-wastegated housing on the truck

 

[fest3er]

I was assuming that I was building that extra boost because the previous owner had possiblly adjusted the WG shut?

I know the original owner have the dealer tweak it for "efficency" towing a goosneck motorhome.....

Again I'm not even sure I found the waste gate? Can anyone shed some light on this.

Thanks-

If you have, or have access to, a digital camera, take a few pics of the turbo and post them.

 

[Missouri Mule]

CWeaver it seems you have found the wastegate rod going the exhauast housing of the turbo. The rod can not be moved by hand needs air pressure as I remember. It could be stuck.

If you have after market hp plate you could probalby reach 42 pis of boost or if the oringinal was re-ground. If you have a wategate and it is working it should be opening around 20-22 psi. If it opens at 20 psi that will be all the boost you will see but I could be wrong about that.

 

[fest3er]

My stock '98 12V turbo has the factory WG setting (18PSI IIRC), but I typically see 26-28 PSI at full fueling, and have seen it reach a hair over 30 PSI a ttime or two. The WG only bypasses the exhaust it can. It can't exhaust everything to keep the boost from exceeding the WG setting; it's a gate, not a bypass.

I've got a 3k GSK, 215 injectors, stock plate slid forward, and AFC slid backward a hair to control smoke. Engine is otherwise stock. It has the auto trans with a couple purple ATS parts in it. And, FWIW, 28PSI is about the max for the stock turbo before it goes out of its efficiency range; that is, it begins heating the air instead of moving more air. Both heat and density contribute to pressure.

 

[Forrest Nearing]

a wastegate is a turbine bypass

 

[CWeaver]

Turbo Pictures & update on boost issue

Looked at the Truck & took pictures this weekend.

The truck Had a aftermarket round, open element air filter.

a DuraLite filter from a larger truck.

I removed It ant took pictures of the Turbo - attached

I put the factory air cleaner housing & a Fram filter (both came in the back of the truck) and took it out for a drive. Now when I step on the throttle had I build up to 30-32 pounds of boost. :-laf I'm surprised a filter can make that much difference. The truck seems happier now.

Per the TDR periodicals article on filter testing they stated that in real world testing (not on a dyno, hood open, w/ giant fan) the factory cold air intake worked best... at least produced the best fuel mileage...



Still interested in whats up with my turbo & if I need to fix the waist gate...

Do you actually hear or feel the waste gate open like on a small car???



Please take a look at the photos & tell me what you can- Thanks !!!

View attachment 70647



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View attachment 70652

 

[fest3er]

... Do you actually hear or feel the waste gate open like on a small car??? ...

Pert near looks stock. You shouldn't hear the WG open. At least I've never heard mine open. It might open somewhat gradually or it might open instantly. Provided the boost line is connected to the WG (and is open), the WG should open around 18 PSI. You should be able to use regulated shop air to test the WG.



I wouldn't be surprised if the WG boost line is plugged, otherwise disconnected or even vented (to reduce boost reaching the actuator). Be aware that if that is a stock turbo, any boost beyond about 28 PSI is from heat--the charge air simply loses density. And taking hot engine compartment air for the engine compounds the temperature problem and emissions.

 

[CWeaver]

Thanks Fest3er:

I'll check to see if the line is plugged.

I know it goes to some contoller / brass elbow by the injectors. like a IAC maybe?

 

[DPashko]

does it have a boost orfice on the wastegate line?

 

[Forrest Nearing]

on a straight piped truck or lightly muffled truck, you can gear when the gate opens

 

[Champane Flight]

Did not see it..

I did not see the line going to the wastegate actuater. I would venture to guess after putting the stock air cleaner back on you have a high restriction, more smoke? If you put aprox 28# of air to the actuater you should see movement of the arm, I am betting someone pinched off the line somewhere to disable the wastegate for more boost. I have a #5 and a boost elbow inline, 4" turbo back, all in stock position, my stock air cleaner would peg on restriction, I pull 32#. .

 

[Kiohio]

An update to my story---
I had McCabe Diesel in New Lexington OH time the engine for me as well as rebuild the vac pump and put in a new front cover gasket and seal and check the KDP.
First rate service.
Time to replace the Stickers LOL
Truck runs great, no more miss!!!
It started better too.
Truck timing was set at 12, bumped it to 16. 5.
I'll let you know how it does at colder temps later on.

Thanks for all the help!!!

KO