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1980 242 GT. A reasonable project.

The replacement head is back from the shop. I'm very pleased with the work that was done.

After a thorough cleaning and inspection, they found that the valves, guides and seats on the exhaust side all needed some work, which sort of led to me letting things snowball a bit. They installed bronze liners in all of the exhaust valve guides, recut all of the valves and seats for a "performance" valve job, did a bit of porting work to clean up the bowls around the recut seats, bled down the cam followers from my old head (the set in this new head had a fair amount of corrosion), and then resurfaced the deck.

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Next, I'm going to chase all of the threads and preventatively install keysert threaded inserts for the exhaust manifold studs.

It'll still be at least a week until this is all back together, but I'll be carefully putting things back together piece by piece. I'm going to be trying out Cerakote air-cure ceramic coating on the outside of the exhaust manifold and turbine housing.
 
Have you thought about putting new exhaust valves in? Seems like exhaust valve failure on whiteblocks isn't that uncommon.
 
Almost all of the prep needed prior to reassembly is done now. Here's a few highlights.


Threaded inserts are in for the exhaust manifold studs, along with new studs.

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I sandblasted the exhaust manifold and turbine housing, then sprayed Cerakote air-cure ceramic coating.

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I also installed threaded inserts in the exhaust manifold, after some thread failures while removing the turbo last summer.

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That left me with a nice pile of refreshed and refinished parts ready to go back on.

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I decided to take advantage of this time to add in a thermocouple for tracking EGT in the manifold to turbo flange.

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I missed this the first time around... might explain the lack of boost control I was seeing :lol:

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So I fixed that with a step bit, carbide burr and sanding wheels.

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This weekend I'll spend a little more time in the garage on it. The only task beyond reassembly is fabricating a new turbo oil return to the factory location. Getting close to driving it again!
 
Nice quality work! Always refreshing on TB to see someone "doing it right".

Those new studs all M10? They look it, unless it's the pics. Also, your threaded inserts are the best type.... I think the original supplier was a company called KEENSERTS. Little threaded hardened barrels with 4 stakes you drive in; in 35 years of industry usage I don't know that I've seen one fail without abuse. Another higher $$ solution even more bullet proof is the TIMESERT, which I've used to repair head bolt threads in iron blocks (thanks to Trick Mick, I miss him).

Looking forward to seeing some dyno data for that 5 holer..... I've got my B5244T5 on a dolly in my shop, when I finally build my 84 242.
 
Thanks! Yep, they are Keensert style inserts that McMaster Carr stocks. I've been happy with them so far (I had to use them in the previous head for the cam cover after I had rampant thread failures and helicoils left me disappointed).

The exhaust studs in the head (link) are 5/16"-18 (head side) and 5/16"-24 (manifold side). The studs in the exhaust manifold (link) are M10x1.5 (manifold side) and M10x1.25 (turbo side). I'm using silver plated nuts and nord-lock washers with both.

I was pretty seriously considering picking up a lower mileage b5244t5 to swap in after running into the issues that I did. I'm still not sure what the right decision would've been, but at least I have a solid head. I can't wait to be at the point where this hits a dyno.
 
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Long story short, this car is still plagued by oil drain issues. Here's a recap.

I decided to remove the existing drain line to the pan and make something that returns the factory oil return port on the block. This was quite a pain, there was very little drop between the turbo and block fitting.

I experimented with a bunch of different fitting, hose, tube options. Almost everything wasted too much vertical space to have any amount of vertical angle in the drain path.

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Here's what I came up with:

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That resulted in this:

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All of this oil came out of the compressor following testing that drain. Obviously, that drain was not working. This was far worse than the first drain I had in place.

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With that, I went back to the drawing board (only after a few months of apathy ignoring the car). I decided to have this be the first practical work I've done with a tig welder also, so it's not pretty.

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Unfortunately, I'm still seeing puffs of oil smoke out of the exhaust after rolling to stop following some higher rpm driving. Better, but still a significant problem.

At this point, I'm only seeing two options here (three if you include parting out the car; four if you also include swapping in the S52 out of my M3 :lol:)
  1. Option 1 is install a scavenge pump.
  2. Option 2 is mount the turbo higher up to allow for an effective gravity drain returning above the oil level (and have to redo just about everything on the exhaust side of the engine in the process). I don't think I'm up for this much work.

Anyone have experience with scavenge pumps, especially related to long-term reliability and use in a street-driven, road-trippable capacity?
 
A turbo sump and scavenge pump is probably the best solution, but how much higher do you think the turbo should be? Could you machine the manifold turbo flange to get a bit more height?

It looks like you could shorten the tube to that sump you have now and give it a bit more angle. That might help.
 
Damn dude, sorry to hear there's still smoke. Can you remind us again what your current oil restrictor setup is (pre-turbo)? It should help if you can cut down oil inlet flow even further.

But I can't imagine that voluminous sump you built is backing up with oil, so there must still be some other pressure differential driving the leakage.
 
Damn dude, sorry to hear there's still smoke. Can you remind us again what your current oil restrictor setup is (pre-turbo)? It should help if you can cut down oil inlet flow even further.

But I can't imagine that voluminous sump you built is backing up with oil, so there must still be some other pressure differential driving the leakage.

I have a .030" restrictor in there, but I've also tried stacking a .035" restrictor in line with the .030". As far as I could tell, it didn't make a difference with or without the second restrictor in place.


A turbo sump and scavenge pump is probably the best solution, but how much higher do you think the turbo should be? Could you machine the manifold turbo flange to get a bit more height?

It looks like you could shorten the tube to that sump you have now and give it a bit more angle. That might help.

Hmm, interesting ideas. I'll take a closer look at the flange to see how much could be gained. I worry that it wouldn't be enough, but that would be nice.
 
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Call me dumb, but that CHRA does not seem to have the oil path within 15 degrees of vertical. Have you tried reclocking the center section?
 
Call me dumb, but that CHRA does not seem to have the oil path within 15 degrees of vertical. Have you tried reclocking the center section?

In the first batch of photos with the drain returning to the factory port on the block, it had to be clocked around 30-35 degrees IIRC just to have a downhill slope toward the block port. When installing the latest iteration of the drain, I did reclock the CHRA. I didn't check it with the angle finder, but it's much closer to vertical now.
 
The only real caveat people see with a restrictor that small is that it could be easily clogged by a bit of 0.016" debris. The counterargument is that if you have debris that big floating around in your oil system after the filter, you've done something else wrong.

I think your current clocking angle is fine on the center housing, judging from the recent photos. There is a V-shaped drain inside the center housing below the bearing, so keeping it close to vertical lets both walls of the V do their thing.
 
Are there any options from Sweden for a purchased 5 cyl. RWD header that would elevate your turbo? I'm not looking forward to building a custom unit (as did Homer, others) but will if necessitated by the supply chain.

Or is there another reasonable explanation for the oil blow by than just a lazy gravity drain and less that ideal clocking?
 
I do think you should try to go smaller than 0.030" on the oil inlet restrictor before making any other big changes.

Went back into my email history and found our exchange to refresh my memory of everything we discussed. Good to see I'm at least consistent with advice! You've already tried stacking 0.030 and 0.035 restrictors but not gone down below 0.030 yet, correct?

From an email last year:

I know whiteblocks make ridiculous oil pressure, and I see that the turbo is leaking from both the turbine side and compressor side oil seals. I'm not sure how familiar you are with turbo seal design, but they are essentially piston rings with quasi-labyrinth seals and deflectors, usually. In the case of the aftermarket GTX28R to 35R stuff they use a ball bearing without any oil deflector on either end. After the oil leaves the ends of the ball bearing cartridge it ideally will drain down into the center housing oil drain cavity, but in reality there is not much stopping it from being forced past the piston rings.

In my experience the off-throttle leakage (especially from both ends) is curable by reducing oil flow into the turbo. You've already done that, and maybe improved the situation, but I think it would be worth experimenting with multiple restrictors in series, and/or smaller orifice diameter. The concern with going much smaller than 0.035" is that any tiny bit of debris could clog the restrictor. That's valid, but the reality is that there is an even smaller orifice hole in the ball bearing locating pin, and two even tinier holes in the ball bearing outer ring, which actually feed the balls at each end.

Stacking multiple restrictors in line will reduce oil pressure and flow, and cut down on that internal spray from the bearing out toward the piston rings. Reducing crankcase pressure might help a little bit if it was overly high, but the oil pressure is essentially at ambient air pressure as soon as it enters the bearing, so all it would do would be to help evacuate the oil drain cavity if the center housing wasn't draining fast enough. In this case I don't think it would help much even if you added a scavenge pump! I think the issue is too much oil flow coming from each end of the bearing and blasting right at (and past) the piston ring seals.

These ball bearing cartridges don't need much oil flow to survive; they do depend on oil for cooling during operation, but water cooling will help somewhat. In my experience it's rare to starve a ball bearing turbo of oil; more than likely it would get overheated and coke formation would become the next issue, but again water cooling helps alleviate that (especially after shutdowns).
 
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