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2008 Suburban HD - 8.1L swap (frankenburban 2.0)

I know when I had a 2013 GMC Sierra crew cab... albeit 5.3L... It threw the same kind of error code with stable track and traction control when somehow a plug cracked. I also had an issue where every month the truck would explode the center of the plug out on cyl 7 and do the same code each time... so id lean towards plug as well...
 
Chevy305 said:
You mean you didn't do a compression test before you installed the engine? :doah:

Did you install new plugs? If you didn't it's very likely that one might have been hit between the transit and install.
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No I did not, for fear of it sitting too long and without oil in there I didn't want to wash out a bearing. Even if I filled it with oil, me cranking it for a comp test won't give enough RPM to spin the pump enough.

I did install new plugs. The engine came with a warranty so I talked with the junkyard about it and will honor their warranty (which is up tomorrow) but the shop owner was pretty straightforward guy so a quick cylinder leakdown test would be great. I don't suspect any ring issue because it has plenty of power.

RootBreaker said:
I know when I had a 2013 GMC Sierra crew cab... albeit 5.3L... It threw the same kind of error code with stable track and traction control when somehow a plug cracked. I also had an issue where every month the truck would explode the center of the plug out on cyl 7 and do the same code each time... so id lean towards plug as well...
Click to expand...

if you had a bad plug I could see a misfire but that wouldn't explain the huge cloud of blue.
 
So a bit of google-fu on the subject had me pondering but I think the issue could be the PCV actually... which is also making the oil pan leak worse.

The 8.1 it uses an internal PCV system and it grabs its fresh air through the airbox with a port in the throttle body itself that feeds to an orifice at the bottom of the intake manifold. Now with the throttle body spacer to go from a 3 bolt to 4 bolt throttle body I am now effectively blocking that port so the PCV is essentially plugged cause high crankcase pressure blowing oil into the combustion chamber and causing my shit oil pan gasket job to leak further. This would explain why its in the high RPM/load range only.

Take a look at the 3 bolt vs 4 bolt differences on Raylar's site:

http://www.raylarengineering.com/intake_manifold.html

Luckily my earlier idea was to add a PCV system so I have the provisions already there, I will still do a comp/cyl leakdown test for piece of mind but if those results are good I can go ahead with pan gasket repair and install a PCV system.
 
Chevy305 said:
That makes a lot of sense. Good thing it's something simple.
Click to expand...

Yeah the question is now how do I route it because there are a million different ways to do this...


uc



uc



uc
 
Option A looks the best.

Main problem with option C is running the line to the airbox. From your drawing, the intake manifold will be drawing unmetered air, and any oil that makes it through the catch can will eventually dirty up the MAF
 
Option A as well. But run a catch can between the valve cover and the intake manifold as that is where your oil vapors will be coming from.
 
yeah I was wondering where I would put a catch can on that setup. I wont be causing a vac leak by having the intake manifold essentially plumbed to the valve cover?

Also I assume I would want to go with a non vented catch can then if I put one between the intake manifold and valve cover.
 
fidelity101 said:
yeah I was wondering where I would put a catch can on that setup. I wont be causing a vac leak by having the intake manifold essentially plumbed to the valve cover?

Also I assume I would want to go with a non vented catch can then if I put one between the intake manifold and valve cover.
Click to expand...
That's right, sealed catch can as it'll see full manifold vacuum. It won't cause a vacuum leak either, that's exactly how mine is setup on my 350 and my L9H.
 
Amazing work. Your the only person I know with a 6L90 behind the 8.1. I got a 8.1/4L80 combo in my 78 el camino that is going in my 74 vette in a few weeks. I really want to put the 8.1 in the vette with the 6L90 oppose to the 4L80. I could only imagine how much more of a thrill it is to drive with the aggressive gearing of the 6L plus the extra 2 gears. How do you like driving it just beating up on while not towing anything? Also can you point in the direction for getting the 6L90 mounted to the 8.1.
 
putting a 6l90/8.1 combo in something else that didnt come with a 6l90 will take some work. You will have to ditch your existing harness for the 8.1 and pickup a gen IV ecu and harness. I like it a lot, I don't beat on it I like putzing around haha.
to bolt the 6 speed to the 8.1 check earlier in the thread for part numbers you need the GM performance kit (or make your own spacer) and longer bolts.
 
quick update, oil pan leak mostly fixed the oil is now leaking out of the CKP. Not sure why in GM's infinite wisdom they thought to put a sensor at the bottom of an oil splash location when all the sensor has to do is read a tooth'd wheel. You would think if they made a new casting for this piece that they would put it up a bit higher so oil doesn't pool and leak out. There is no gasket provided and it has an o-ring but that doesn't seem to hold the oil back, I tried a few different O-rings but it didn't seem to matter. RTV helped but I think I need to be more liberal with it...

Also the catch can worked great! almost too great with a 800 mile round trip I filled the catch can, 1/4" may be too big for the PCV hose, I will run a reducer to 1/8 and try again but that cleared up the oil burning issue for sure.
 
VisionxOrb said:
Its been a couple months.... Im jonesing for an update.
Click to expand...

Yeah it has been a while... I have put about 5,000 miles on it and done some mild towing with that too.

Did some driveway clearing with the truck in Dec:

https://www.facebook.com/video.php?v=392253837875218

I've ditched the oil can for the moment, I checked to see if the PCV port was plugged, it is not plugged - I need to route the catch can setup differently. Instead of mimicking the 6L setup I need to utilize the port on the front of the intake manifold that leads right to the crankcase - there is a 1/4" NPT plug for where the oil drain is for the medium duty accy drive setup for the versions equipped with a belt driven air compressor. Also this requires me to plug the port at the bottom of the intake manifold but if I do that I need to remove the intake manifold off the truck and while im there I will "have to" chop off the plate and let the intake manifold breathe a bit better. Common modification - but Raylar wants 1000 to do this however I got expert aluminum tig welders locally who are good friends - so should not be a big issue and can be done for beer money. So right now its just running the traditional PCV setup that is stock with the 8.1

After that I had a minor fuel leak at the rail which was a minor fiasco in the sense of getting correct parts of facebook groups (whole nother issue of stupidness...) - no fire but the o-ring failed at the crossover tube that goes from the driver side fuel rail to the passenger side rail causing it to weep fuel, very noticeable when you get out of the truck and go to walk towards the front of it, so I took it apart and had a friend weld some AN fittings on both sides and connected it with a stainless braided hose - now it cannot leak and cause fires which is a plus.

I wasn't going to attempt another pan job so I had a local shop fix the oil pan leak and fixed it with my purse, meanwhile I had them run a leakdown and cyl comp test but I don't think they did it right, they showed 135-145psi across the cylinders with 15-25% leakage. This thing should run like ass imagine but it runs really nice, except it seems to have a slight miss at idle. The oil pan leak is fixed but the CKP leak is still constant and I cannot get it to stop leaking for the life of me - quite frustrating.

I had a total of 4 or 5 lean misfires that registered codes for high load/rpmwhich makes me worried, I'm going to perform another comp test next week when I have some free time (work has been very busy recently) but here was my recent oil analysis sample:

uc

the column on the far right was when I originally got the engine and pulled as much oil as I could from the oil filter, the grey column is the average of the 2 tests Ive done

I was ready to do another engine tune but I will wait and see how my comp test goes not to mention recently the TQCV is making some noise when stationary for a while, (2-3 or more minutes) I get a grumble like a bag of stones...when you give it some revs It seems to drive okay and go away with more revs/load but is only happening when in gear, (not P or N) but I checked the flexplate to tq converter bolts and they are tight as can be however its quite worrisome because the noise is getting worse. I wonder if the pump is failing in the TQCV...

I have a trans cooler line leaking that I need to replace, its not bad leak by any means but any leak isn't ideal so I will take care of that and possibly do a pan drop and filter job to see if that helps the noise. Other than that I dunno if I am down to a custom tqcv route again...

not out of the woods yet!
 
sorry I should specify made a simple mistake:

The grey column on the far right is what they should be at/normal PPM
The white column on the middle right is when I originally got it, all oil sourced from oil filter
the white column on the left is current sample
grey column in middle of both white columns is the average of the two samples.
 
If you want something done right you do it yourself, hence why I never take my vehicles to shops in the first place because I'm just as competent or more than competent than their mechanics but when I pay for things done I like that they are done correctly because time is money and I hate wasting both.

so I bought a compression tester

uc


And did my own test to verify their claim. Unplugged CKP, unplugged connector to coils, unplugged fuel injector connectors then put the the battery on the charger only after I warmed the engine up to get more accurate readings.



plugs looked fine too, maybe a touch lean but nothing scary.

Replaced the leaking trans line and now lets hope that everything is just peachy and I can go get some dyno tuning done to the engine just to be safe.
 
4 things left now:



1. That stupid rattle!!!!!

I didn't notice the noise until I had the exhaust "fixed" it leaks still a bit at the welds and when you strike it, it rattles. Maybe the root of the noise???

it is a bit hard to tell in the video but you can hear it more profound in person, you slam the door you can hear it a little too. (I'm kind of grasping at all straws here)



2. OIL LEAKS! drive me nuts! It seems to be coming from the rear oil pan, the filter and the CKP sensor - which leads me to think that this is crankcase pressure issue. No vacuum leak now (gave up on the catch can) which also leads me to believe that I am still blocking a part of the PCV system. I checked with some mechanics wire and a USB boroscope for your phone (which was well worth the $14) and the one in the bottom of the intake manifold is not plugged. However I am blocking the fresh air port on the intake manifold with my throttle body adapter. OBSERVE!

1521208251_phopto_mmthumb.PNG


335-551513.jpg


the adapter blocks this square off...



look at the throttle body for the 8.1 it has a port that leads directly there and is before the throttle so it sees full vacuum all the time regardless of throttle position.

1521208560_tb-up-view_mmthumb.PNG


So I either need to drill and tap for a 1/8" NPT fitting that gets to that port in the manifold or go through the spacer somehow. I already have a port I made on the intake tube for the fresh air so a hose will not be a big issue seeing air before the throttle plates.

3. Clutch fan bearing are bad (has some wiggle to it) and the blades are a bit bent and rusty so being that this was the only junkyard parts I used on the swap I will just replace this and move on...

4. With all of this taken care of THEN I can get a dyno tune understand the power output and give you a proper burnout video (when I find a 2nd set of wheels with bad tires on them because I want to go with a set of winter tires for this beast because BFG T/As are terrible on icy roads)

initial burnout test in the driveway yielded positive results a good solid #11 is on the driveway now...
 
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