98 GMC Suburban Revival

[Robyn]

Why are you ripping the inner fender out ????

[Yukon6.2]

I decided seeing i will be in as far as i am...
The injectors are coming out for pop testing,i have a couple sets of used ones.I will try and get a set that are all popping close to the same numbers.
Pulled the turbo off as well.
Last night i got it striped down,intake off heads taped up,lines off and labeled,cardboard cutout of the injection pump mount made,line scribed,three bolts out of the injector gear successfully extracted.Pulled all the glow plugs.Surprise surprise they all matched and look new.AC Delco's even the glow plug wires are in great shape.It was a loved truck at one time
Questions...
What PSI should the 6.5 injectors be popping at?
What color loctite on the 3 injector gear bolts?
I may be going for a walk around a bone yard,so if i want to consider a Holset 35 turbo what ones should i look for and what else is required?
The outside of the injection pump is ugly,may even be the original.Still is wearing a PMD
A local gal with a cleaning company may get some time to steam the remaining interior parts i didn't scrub.Headliner,door panels, rear side carpeting.
Thanks All

[Robyn]

Blue loctite on the pump gear bolts
Clean the threads with BRAKLEEN and blow out threads..flush a second time with Brakleen
Wash the bolts with same and blow dry too.....

Pop pressure should be in the 2000 to 2100 range
I have seen them a bit less and a bit more.
Main thing is having them all close to the same and in the range.

On used pumps I have always tried to keep the pressures on the lower end of spec....A bit easier on the IP......

Can't help you on the Turbo.....I have not swapped any over from the GM X series.

Another thing on the injectors is to have a nice CONE shaped spray pattern...NO PEE STREAMS OR DRIBBLES.....Just a nice clean spay and then shut off.


Ahhhh.....It does not hurt a thing to put a bit of NEVER SEAZE on the glow plug threads....

I have seen these !@#$% stuck so tight that they snap off when trying to remove them.

When you get ready to restart...
Leave the plugs out and spin the engine to get fuel mist blowing from the plug holes.

Saves the starter, batteries, Patience......and makes the job waaaaay easier.....A couple of 15 to 30 second spins will get the task handled just fine.....

The engine should start right up and run.....may have a few little air bubbles that will pass and cause a bobble or two....but really makes life much less tedious....

[arveetek]

I may be going for a walk around a bone yard,so if i want to consider a Holset 35 turbo what ones should i look for and what else is required?

I just put an HX35 on my 6.5L. I would suggest looking for one off a 1994-2007 Ram Cummins. 1994-1998.5 used one version, and 1998.5-2007 uses a slightly different model. Either one will work.

You will need an exhaust downpipe adapter, like this:

https://quadstartuning.com/collectio...wnpipe-adapter

I also picked up this oil feed adapter:

https://quadstartuning.com/collectio...let-adapter-v2

The turbo will bolt directly onto the exhaust manifold.

I also installed a Turbomaster waste gate control; I have no idea what application my turbo came from (bought it used through a buddy who knows a guy), but I think it was an industrial application. There were no mounting bosses anywhere for the waste gate controller, so I had to get creative and make my own mounting bracket.

Then you will have to modify the top air hat on the intake; I had to cut about 2" off the intake pipe that connects to the turbo since it was too long.

Then you will have to modify your air filter setup. The stock turbo has a 3" inlet; the HX35 has a 4" inlet. For now, I have ditched the factor air filter setup completely and went with an aftermarket filter utilizing some universal silicone elbows and such. Don't forget you'll need to plumb the CDR hose into the intake somehow.

Here's my current setup:










I still need to modify the air filter setup so that it is not sucking in hot air from the under the hood.

The sound from this turbo is absolutely amazing! You can hear the whistle at all times above idle. I have the Turbomaster backed all the way off, and boost seems to max out around 15 psi.

An intercooler is next on my list.

Casey

[Yukon6.2]

Thanks for that info Casey
Turns out i already have a turbo sitting on a 2000 53 block that is complete the block is split 16" down the water jacket.I replaced it in a 1 ton i have.
Got the injectors pulled today and they tested from 1600 to 2100 with 3 in the upper range.
Pulled a set out of a core engine and they were all around 1950 to 2100 except for one at 1500. That one turns out to have a different body number of 972. The rest were all 973.
This is a pretty old tester that has been sitting in a shed for years so the actual pressures are probably different.
I will pick the best 8 and start putting it back together.
Some injectors were barely tight.
I am glad i spent the extra time to test the injectors,hopefully it runs better once it all back together.
Fingers crossed i may be able to get a long day in on it tomorrow.

[DmaxMaverick]

Getting all the injectors within a narrow range will certainly add to smooth running. 1600 - 2100 PSI is a hot mess. The odd number and lower pressure is probably a 6.5 N/A injector. 1950 - 2100 is OK (within Gm spec), but I like them within 50 PSI or less. 100 PSI would be a set that just gets by, but I'm OCD like that. It sounds like your tester is just fine. It's more important to get the trend right than the actual pressure, which is probably accurate enough, considering the pressures you're seeing.

[Robyn]

I am with Maverick on this ....
Having the injector pops all very close make a smoooooooooooooth runner.

This also helps keep unwanted cylinder to cylinder timing variations from causing a lot of extra torsional stress on the crankshaft too..

[Yukon6.2]

My thoughts were to match them to the firing order
Ramp up to the highest then back down to the lowest.

[DmaxMaverick]

You must be very careful with such detailed combinations. They're known to cause catastrophic events, like slowing Earth's rotation or causing tsunamis.

[Robyn]

They need to be all the same to maintain the cylinder sequential timing......

[JohnC]

So, what you want to do is order them from highest to lowest, number them 1 through 8, then, following the firing order, install injector 1,3,5,7,8,6,4,2. That way you minimize the difference between successive cylinders. I think....

Power oscillations will approximate a sine wave.

Do you think we could be overthinking it?

[DmaxMaverick]

....Power oscillations will approximate a sine wave.

Do you think we could be overthinking it?

Yes, and yes. I thought of the same thing, and considered the possibility of actually creating a harmonic condition with no resolve. I suspect the generous OEM range spec of injector performance has allowed this to happen several times (monkeys + typewriters theory), and may suggest an explanation for some failures that are yet unexplained. Any harmonic condition can be broken by introducing a random. The same argument can be made with the type of dampers available, static rubber or fluid. If a designed harmonic condition exists, a static rubber damper will allow it to continuously repeat, while the random behavior of a fluid damper would certainly break it. Not unlike spinning or rolling eggs on a countertop. Boiled and raw eggs still contain all the same components and mass, but they behave very differently to the same energy applied to them.

I think it's either best to match them within a very tight range, and/or install them randomly. Although, I doubt it really makes much difference, with injector component and test equipment variations. A simple tester only shows what pressure the injector pops, with no consideration for volume, dwell time, or temperature. Spring performance and fuel viscosity can be greatly affected by temperature, so unless we are testing the injectors in the same environment they will be operating, we really have no idea what they are actually doing on a running engine. I never gave it much thought, and perhaps that's for the best. Just do the best we can with what we have, and trust the engineers did their duty.

[Yukon6.2]

Fuel viscosity...
Yesterday i was thinking about that,the fuel for the test was winter fuel thin and dry.
I ended up with 1950 as the lowest and 2075 as the highest.
i was hopping to finish off the truck last night,but had to go home to eat and start a fire,then my back started to complain about being hunched over the fenders.By the time i was done eating i was fat and happy so the couch won.

[DmaxMaverick]

Using lower viscosity winter fuel may more accurately (less inaccurately) simulate a running environment. As temperature increases, fuel viscosity decreases, and mechanical tolerances increase. I'm curious to see test results using straight #2, as used in a typical test.

[Yukon6.2]

It's running and driving...
It still has some quirks.
It threw a couple codes after the first few miles
P0307 cylinder 7 misfire
P1216 fuel solenoid response time to slow
I changed the injector with another tested one
I think the running temp is low,maybe no thermostats which i will check with a temp gun today.The scanner was reading 183F after running for a while.Still getting white smoke that smells of unburnt fuel.Black smoke when you put your foot in it but now the Burb will accelerate when you put your foot in it.
One tool i don't have is any compression testers for a diesel.I am hoping number 7 is ok and will come around with a different injector.I thought about removing the fan as a test to try and get some more heat into it.On the gauge it never got above the big mark between the 160 and 210 so around 180 ish.

[Yukon6.2]

So the Burb had some chineses thermostats which i replaced with some used Delco ones.It made a difference.The chineses ones would open and start to circulate right away.
If you hold the revs up around 2000 the exhaust pretty much clears up,but it doesn't take long at idle to start smoking again.Un burnt fuel smell.
No codes were tossed, i worked it up a 3 mile hill topping it at around 90mph the scanner reading 193 F so it is running warmer.
Any magic injector cleaner to try?
To me the smoke points to poor injectors,one puffs smoke a bit quicker then the rest.
No massive blow-by,no popping sounds of bad valves.
New Bosh injectors on a Canadien online shop are $80.00 each which doesn't seem too bad.In CAD and free shipping.
Now a tranny question...
When the 3-4 shift happens under power it is a definite hit.I haven't driven one of these trannys so no idea on whats normal.
Thanks for any ideas,suggestions ect.

[Robyn]

So....No codes at all ?????

That is a good thing.

You pop tested the injectors.....

This test should have eliminated any bad injectors.....This said there can be other issues with the squirts other than the pop pressure.

Does the engine misfire at Idle RPM ???

If an injector is dribbling after its initial firing it will contribute to smoke

An injector that is peeing a sloppy stream will make a smoky exhaust.

Injectors should spray a nice even CONE of fuel mist when they "pop" there shouldn't be a sloppy bunch of droplets ..

Can you isolate the cylinder/s that are causing the issue...

The other issue could be in the IP.....But lets not go there yet...

Did you run a compression test on the engine ????

If you did not....it may be a good idea just to be sure we are not chasing the wind....

My gut says that the nozzles on some of those squirts may be in poor shape.....

Does the engine idle smooth ????
Does the engine start up "Clean" ??? or is there a big skeeter getter cloud when it fires off.

Good compression with good squirts and all 8 glow plugs in good shape should produces a nice clean start with little to no blue smoke from the exhaust pipe.

Since the injectors were used....there is not a good starting point here to work from....Other than replacing the squirts with fresh parts that are known to be in top shape....

Just having the "POP" pressure in the acceptable range is not the entire story.

At the time of injection the cylinder pressure is high......so the actual operation of the injector may be totally different than when they are out on the bench cold.....

[Yukon6.2]

Yes no codes on the last romp,i drove it pretty hard.
It does idle like it has a miss.
The testing i did eliminated the worst injectors out of 16,two original ones mad it into the pile that got used.Zero history on any of them.I was mainly watching the pop pressures.The spray pattern was not the perfect cone you would want to see,unfortunately.I was hoping the fact the tester was old and has issues might have accounted for poor sprays,i know wishful thinking.
The IP is a low mileage unit,i know the guy who bought it new and installed it on the engine that ended up in my Tow truck.If it had 15K on it that would be lots.
I don't have a compression tester for diesels i may try and round one up over the weekend.
The initial start from cold is smokey ,but seems to start good in the cold.
Gut feeling is the engine is healthy,no excessive blowby decent power when you romp on it,no popping in the intake or exhaust to point at a bad valve.
I hate to spend the $640 on a new set of squirts on a gut feeling.
Thanks Again on the ideas and pointers

[Robyn]

Do you have a diesel shop close that can check the injectors out ???

Pop pressure and the condition of the actual nozzles are two different things..

Pop can be fine and the nozzles can be crap.....

[DmaxMaverick]

Sounds like sloppy injectors, at least.

You don't have to buy all new injectors. You have a tester, and you can rebuild them yourself. Nozzles are cheap (a good set should be less than $10/ea, stay with OEM grade, don't be tempted with "40 HP marine" nozzles), and it isn't complicated. You have enough injectors to sort through and select the best parts of them, and build a good set with new nozzles. Measure the shims so you know the range you have available. Springs can be inconsistent, use the shims adjust the pop pressure. Keep the bodies matched, and only mess with the nozzles and internals. Set a target pop pressure/range, then mix/match springs and shims to get them there. Keep notes for each injector, springs and shims, so you can go back and swap them to get the results you want. If you have bad OCD, it can get tedious, but it's worth the time. Or, you can just replace the nozzles in 8 injectors that pop where you want, which is what most commercial rebuilders do, then test them. Spend an afternoon, and save yourself $5-600.