89 951 engine overhaul

[four0four]

Well, it's long past due I stuff all this into a thread of my own. I've certainly gotten a lot out of others' threads like this, so I'll try and document some of what I come across...Maybe even ask some questions along the way

I planned to pull my engine over the winter - it's been out for, oh, most of a month (by April). Nothing huge, just one too many dry seals and enough crud built up that I went for it.


todo list now looks something like this:

• M030 front strut refurb

• Turbo refurb (K26/8 hybrid from Evergreen)

• Tial 38mm

• Rod bearings (ACL)

• Forged rods...

• Rings?

• Every damn seal

• Clutch (930? Cup?), PP (KEP1), associated bearings

• Oil cooler and lines

• VEMS plug-and-play

• Steering rack reseal

• Control arms

• Tie rods

• Head refresh (has new springs, plus MM's "insurance" inners)

• Voith's balance shaft rear seals

• Window seals on both doors (completely dryrotted, scratched the windows!)

I've collected..Most of those parts, but for the rest I'd like to see what's going on inside the engine before making decisions. So, some progress:

Out!

out.jpg (2.94 MiB) Viewed 5374 times

Mounted:

mounted.jpg (2.57 MiB) Viewed 5374 times

My janky RTV balance shaft repair seems in decent shape:

rtv-bshaft.jpg (2.7 MiB) Viewed 5374 times

I've only pulled the #2 bearing, here's what that looks like:

num2_bearing.jpg (2.49 MiB) Viewed 5374 times

And on the reverse (side in compression/rod side):

num2_bearing_rev.jpg (2.1 MiB) Viewed 5374 times

I'm an amateur, but this looks shockingly good. Maybe less the marring on the thrust side...not sure what to make of that!


Finally, ....A surprise washer:

wtf.jpg (2.47 MiB) Viewed 5374 times

Findings so far:

- Cast rods
- I forgot to do a leakdown test again - #3 had high (15%?) leakdown before I pulled the motor. Looking at the bores, probably a valve?
- oil pan baffled is cracked up, so going to need to find a new one.

Bores are here, I don't need 8 images in-line!

[Tom]

Great post -- looking forward to seeing your progress. And might I just say those are mighty spiffy intake port covers!

Everyone has their own opinion, so take this with a grain of salt, but I'd either leave the rings/bores/pistons alone, or plan to do all three. I know people can get away with it, but for all the effort it takes to get this far, I wouldn't trust new rings to seat in old pistons (worn landing?) against worn bores. Only way I might try is if I knew the existing rings were bad, in which case trying a new set of rings is fairly harmless (other than the time and effort). The bores do look pretty good. Summit sells reasonably priced bore gauges if you wanted to check dimensions, etc.

Kep 1 and Cup disk is the way to go! I highly recommend them if you'll be sneaking much over 300rwhp out of that turbo.

What's going on with that alternator?

Are you running VEMS now? If not, curious why you'd want to switch over? With a k26/8 turbo, a good set of chips will give you factory smooth power in all conditions with none of the fuss and tinkering that seems to go with stand-alones in general and VEMS in particular... On the other hand, if you're doing it because you like to tinker with sensors and maps, etc., I totally get that.

I'd ditch the sample tube thing on the cross-over too. A lug nut will cap it off.

You do have to wonder about that washer. Unless someone dropped/left it in there by mistake, washers can't get loose unless the bolt it was under is also bouncing around somewhere.

[four0four]

Great post -- looking forward to seeing your progress. And might I just say those are mighty spiffy intake port covers!

Was wondering if you'd comment on that. Not my design, but...oh, it's yours!. And thanks

Everyone has their own opinion, so take this with a grain of salt, but I'd either leave the rings/bores/pistons alone, or plan to do all three. I know people can get away with it, but for all the effort it takes to get this far, I wouldn't trust new rings to seat in old pistons (worn landing?) against worn bores. Only way I might try is if I knew the existing rings were bad, in which case trying a new set of rings is fairly harmless (other than the time and effort). The bores do look pretty good. Summit sells reasonably priced bore gauges if you wanted to check dimensions, etc.

Yeah, I'm back and forth on this. And very aware of my laymanship! I have a set of bore gauges, but I don't have the mics in that range. I doubt my calipers, nice as they are, are up for the task...My big worry is that I get this back together and there's still noticeably more leakdown in #3 than the others.

ETA: I *can* catch a nail (they mean "feel with a nail", right?) on the score line in #4. Maybe one of the others. Disappointing, cause there aren't many lines.

Kep 1 and Cup disk is the way to go! I highly recommend them if you'll be sneaking much over 300rwhp out of that turbo.

TBD what power comes out of it. I'm hopefully building things such that I can tinker a bit and not worry overmuch about the internals. Cup over 930?

What's going on with that alternator?

Hah, I was browsing some Bosch catalogs and decided I'd try to fit some other random alternator with the same bolt pattern. Turns out, they don't show you the Z direction. I'd need to remove too much meat from those bosses to make things fit, so it's probably a wash...

Are you running VEMS now? If not, curious why you'd want to switch over? With a k26/8 turbo, a good set of chips will give you factory smooth power in all conditions with none of the fuss and tinkering that seems to go with stand-alones in general and VEMS in particular... On the other hand, if you're doing it because you like to tinker with sensors and maps, etc., I totally get that.

I'm not, there's some unknown Kokeln (dump here) chip in there now. I want/ed something that will close the loop on AFR, and let me datalog, and...I've only just gotten over the idea of spending 1.5k on *another* 8-bit ECU. If I go any more DIY I'd be laying out a board instead of working on the car...Speeduino is a great idea, but the code leaves a little to be desired. If I had 30 hour days!

I'd ditch the sample tube thing on the cross-over too. A lug nut will cap it off.

That's more elegant than "grind it off and weld it over", I suppose...

You do have to wonder about that washer. Unless someone dropped/left it in there by mistake, washers can't get loose unless the bolt it was under is also bouncing around somewhere.

It's a weird size too! Maybe from the baffle? I didn't look too closely. There was some other minor junk too, seems that the screen did its job

[Tom]

First of all, stellar quote work. You need to give a class on that.

I tried measuring the bores on my 3 liter with a ton of tools, but nothing came close to real bore gauges. Only way to measure bores. But I hear you on the leak-down. If the valves all look good, then maybe do the Nikasil bores so open up piston and ring options... Again, just me, but I would lose sleep doing all that work and then hoping that new rings will seat and fix the issue. They very well may, but then again, maybe not. One score line wouldn't be enough, alone, to sway me. My old 2.5 had great leak down and made tons of power, and it was scored way way worse than yours. But it's part of the equation for sure....

Yes, I'm a cup over 930 kind of guy. Same risk-averse reasoning. Most motors do fine with the 930 disk, but some have problems where the clutch won't release all the way. I think, but am not 100% sure, that it was @chris white who discovered that excessive thrust washer movement (axial play in the crank) allows the crank to pull back enough to stop the clutch from disengaging. I suppose if you change the main bearings, that unlikely to be an issue (now), but in my mind it's not worth the risk when there is a risk-free option designed for the car that works every bit as well. I've been fine for years with my KEP 1, but you might consider a firewall brace since the motor is out.

I can datalog with my Vitesse set up, and his tuning is second to none. I have a Link Extreme G4 with harness, never used, I'd sell cheap for the cause. It's the prior generation, but still could compute circles around VEMS. The harness was prepped by Neil Harvey at Performance Developments for this ECU.

I repurposed that exhaust sample port for my Laust EGT sensor, which I log with the Zeitronix. I've also used it to check and log back pressure under boost. If you will never use it though, weld away. (p.s., is Laust still around -- somebody should invite him over here!)

[four0four]

First of all, stellar quote work. You need to give a class on that.

Easy! Either: Spend too much time on mid-00s boards and figure it out, or just scatter

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I tried measuring the bores on my 3 liter with a ton of tools, but nothing came close to real bore gauges. Only way to measure bores. But I hear you on the leak-down. If the valves all look good, then maybe do the Nikasil bores so open up piston and ring options... Again, just me, but I would lose sleep doing all that work and then hoping that new rings will seat and fix the issue. They very well may, but then again, maybe not. One score line wouldn't be enough, alone, to sway me. My old 2.5 had great leak down and made tons of power, and it was scored way way worse than yours. But it's part of the equation for sure....

Oh, my bore gauges are the kind you need to measure after locking in. Not the kind with a built-in dial indicator. Anyway...I'd really like to be able to inspect the rings without disturbing everything - That, and since I've cast rods I'd like to pull those and swap in Molnars (...reminds me I need to swallow the eBay scalping pill and get a set...). I'm not sure how likely it is that I pull and re-install all the old rings without incident! I'm all ears for advice there though...

Yes, I'm a cup over 930 kind of guy. Same risk-averse reasoning. Most motors do fine with the 930 disk, but some have problems where the clutch won't release all the way. I think, but am not 100% sure, that it was @chris white who discovered that excessive thrust washer movement (axial play in the crank) allows the crank to pull back enough to stop the clutch from disengaging. I suppose if you change the main bearings, that unlikely to be an issue (now), but in my mind it's not worth the risk when there is a risk-free option designed for the car that works every bit as well. I've been fine for years with my KEP 1, but you might consider a firewall brace since the motor is out.

I think I read some threads that came to that conclusion. Was going to measure axial play and decide then, but if there's no significant benefit from the 930 disk over the cup I'm not sure there's any sense going with it.

As for the firewall brace...I'm reticent to put more holes in the firewall, but I suppose I could toss an o-ring in there. Is this much of a concern?

I can datalog with my Vitesse set up, and his tuning is second to none. I have a Link Extreme G4 with harness, never used, I'd sell cheap for the cause. It's the prior generation, but still could compute circles around VEMS. The harness was prepped by Neil Harvey at Performance Developments for this ECU.

Yeah, pretty sure VEMS is the older Megasquirt AVR-based design. Not fast! I'd take you up on that if I hadn't already put down money for VEMS - I'm sure it'll work fine

I repurposed that exhaust sample port for my Laust EGT sensor, which I log with the Zeitronix. I've also used it to check and log back pressure under boost. If you will never use it though, weld away. (p.s., is Laust still around -- somebody should invite him over here!)

Ah! That's a good idea. I'd had characterizing backpressure percolating somewhere the back of my head, so I'll avoid anything permanent here

Laust was around as of 8/21 according to my PMs over on Rennlist!

[chris white]

did I hear my name being mentioned or did Tom just want to wake me up!
I had some issues with a customer supplied 930 disc, installed it several times and it never worked correctly. At one point the 930 disc was cheaper than the cup clutch so some people liked it. I have used the cup clutch on cars with 400rwhp with no issues - even on the track. The reality of it is that if you are competent with your shifting and clutch work then you wont have a problem with just about anything, if you speed shift or slip the clutch while making boost you will toast anything.

As for Tom's offer on the Link - I really like the stuff (I'm a dealer) - if you get Tom's unit i'll help you out with any questions / tuning gratis (because Tom is a good guy!)

If you feel the ridge at the top I can guarantee that it gets worse as you go down the bore and you have some taper. Taper is what really kills the rings - constant change in bore diameter, however slight, flexes the rings every cycle. But the simple test it - does it pass oil out of the AOS? if so then its rebuild time, if its bone dry then leave it alone.

[Thom]

There seems to be 2 versions of the Cup disc, the later one featuring a supposedly beefier 4 spring set up rather than 6 smaller springs on the first version. I posted some photos of both discs in another thread as I replaced the clutch last Summer. Initially the clutch would barely disengage but after a couple of thousand miles it feels just fine, so I guess it just requires some bedding in - and I always baby my clutches and I don't remember slipping it "badly" at any moment. So far it holds the power of my 16V engine fine, which probably makes around 500hp at the moment, thought that's with a KEP 2 pressure plate which is not super soft.

Another vote here for the Link G4 ECU. Happy to provide feedback if needed, even if I'm not a pro like Chris.

[four0four]

Speaking of a clutch, here's what came off:

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clutch.jpg (331.54 KiB) Viewed 5306 times

@Thom - you mean two versions of the 930 disk? I poked around in your history but only found pictures of those. The cup disk has been revised for sure, there's at least two slightly different versions floating around the internet. I don't think I'm in danger of approaching 500hp.

About the ECU: I'd be sold on the Link by now if I hadn't pulled the trigger on VEMS some weeks back - if I get in a big enough fight with it, maybe I'll revisit that

If you feel the ridge at the top I can guarantee that it gets worse as you go down the bore and you have some taper.

I'll have to check this when I'm back at the shop...Will also try and get a profile on the bore along its length too, to get a sense of things.

But the simple test it - does it pass oil out of the AOS? if so then its rebuild time, if its bone dry then leave it alone.

I'm afraid we're a little past testing that I've got the cleaned and disassembled AOS sitting in my kitchen (...). Are there any tea leaves on the block I could read?

Also, is any of this moot in light of new rods? I'm not inclined towards confidence in cast bits older than me...and confidence is why I'm rebuilding this!

[Tom]

Realistically, to replace the rods, the pistons need to come out. Once the pistons are out, my confidence would be pretty low on either new or old rings working well on old pistons in old bores. If confidence is why you are rebuilding, I'd either rebuild the whole thing or leave the bottom end alone and just reseal it. Of course, it will never be easier than now to sleeve, hone, or coat the bores so you could install the forged rods along with new pistons and rings (and polish the crank and put in new main bearings).

Your pictures inspired an idea that I'll be posting soon.

[chris white]

Realistically, to replace the rods, the pistons need to come out.

If you can change the rods without taking the pistons out you're a magician!