89 951 engine overhaul

[four0four]

Thanks

Filled the coolant and pre-filled the oil coolers this afternoon, I think start up happens tomorrow

[Tom]

Thanks

Filled the coolant and pre-filled the oil coolers this afternoon, I think start up happens tomorrow

Video it! That's must-see TV

[four0four]

Well, not tonight. Made oil pressure just fine (waiting for that was a feeling...)...and the fuel pump started leaking aggressively out of the crimp

Shooting some messages out to local folks but it seems like I'll have to wait. Bah!

Edit: Eh, impatient. Ordered a Bosch "FP 165" (~200lph, stock current draw, with documentation!) with fast shipping from FCP...

Edit the 2nd: ...I need to remember to double-check this. FCP really likes quietly switching cart contents between logged in and logged out contexts. I apparently ordered the stock pump, which is fine, but ugh.

[dr bob]

From 928 owners who have almost 2x the places for fuel to leak, the tribal advice is to install a switched jumper in the fuel pump relay socket so you can run the pump for testing at will. Pressurize the system with the pump and check for leaks well before you think about starting the engine. I tend to search with both hands and nose, feeling and sniffing to try and detect any leaks. Fingers around every connection, feeling for leaks. Sniff your fingers for fuel fragrance. If there's any hint at all that there's a leak, wrap the connection in a strip of paper towel and let it capture any possible leaking fuel there while you continue the search. Real latex gloves soften quickly in the presence of gasoline, making them ideal for this inspection duty.

Doing this with engine cold means smaller leaks won't evaporate before you discover them. Cold means I'm much more likely to reach into tighter places to search too. Much less stress than watching and listening to a first-start engine at the same time too.

If you have a fuel pressure gauge, connect it and watch the pressure after you switch the pump off. It should hold well if your connections are good and the pump check valve and the fuel pressure regulator are holding well.

FWIW, this initial testing is done outside if possible, with a charged garden hose at the ready just in case.

----
In my personal experience, a very thin coating of teflon thread sealing paste makes all the difference when using banjo or ball-seat connections in automotive duties. It doesn't seal so much as lubricate the sealing faces, so there's no scratching or galling as you tighten the nuts or banjo bolts. Banjo washers can be reused. A tiny bit on the connection threads makes getting fittings apart later a LOT easier too. Loctite has the stuff in small tubes, or I have a small jug that gets used for other hydraulic and industrial instrument connections. Absolutely no risk of shreds of Teflon tape fouling an instrument. Tightening torques can be reduced as the friction decreases. The gas and steam turbine guys use a $$$ nuclear-grade non-metallic anti-seize for the same duty as well as for 'normal' anti-seize duties.

[four0four]

Wow, thanks for all the info @dr bob

I just ran the pump right from a benchtop power supply to prime everything, very convenient.

There's one verrry slow leak where I had to modify an imperial hard line <-> AN6 adapter to 10mm, I'll need to put a new ferrule in and probably clean up the seat. Will try and track down some teflon paste for sure!

As for first start - I didn't video that (sorry!), but my folks were visiting from across the country this weekend, so we took a half day to get the last bits figured out. Seems to run well (better maybe than I anticipated), once I remembered to plug the coil back in...

Here's a very short video that should work! Ran it in on BR30 for ~25 mins at 2-3k, it's got a fresh batch of VR1 in now. Oil looked shockingly great coming out, better than expected really. New belts are noisy...And the exhaust is half unbolted :')

Will borescope it later, and I've an oil filter cutter tool on order, but really the next steps are putting the front suspension back, a ton of misc crap, and (ugh) the weather stripping. Not engine rebuild things

edit: idle vacuum is also not what I'd like, but it was cold last I checked that, and maybe as the rings seat better it'll improve? idk, out of my depth on that one.

[four0four]

Borescoped, results are here.

Not terrifically happy with this, though it looks much better in person (I was lazy, just snapped pictures with my phone). I assume this is largely detritus from assembly that causes the marks. Obviously cannot really tell if any are problematic, and I might be getting hung up on aesthetics, but it's kinda a bummer that the bores were cleaner coming out of disassembly than after break-in.


Probably going to continue to run it and hope everything works out, but it does have me rethinking the wisdom of driving down the Rennsport in a few weeks. Thoughts?


edit: also the amount of oil present is a bit weird.

[ealoken]

Borescoped, results are here.

Not terrifically happy with this, though it looks much better in person (I was lazy, just snapped pictures with my phone). I assume this is largely detritus from assembly that causes the marks. Obviously cannot really tell if any are problematic, and I might be getting hung up on aesthetics, but it's kinda a bummer that the bores were cleaner coming out of disassembly than after break-in.


Probably going to continue to run it and hope everything works out, but it does have me rethinking the wisdom of driving down the Rennsport in a few weeks. Thoughts?


edit: also the amount of oil present is a bit weird.

Scores like that seems excessive vs the amount engine has run.
How did you gap the piston rings?
How did they clean the cylinders?

[four0four]

Scores like that seems excessive vs the amount engine has run.

agreed >_>

How did you gap the piston rings?

Gapped them to Mahle's spec (0.7mm iirc) with a hand ring gapping tool, deburred and checked em with magnification. I did mar the walls a bit in installation, but once everything was installed proper, rotating it didn't cause any new marks.

How did they clean the cylinders?

The machine shop? No sure, but I cleaned them with brake cleaner and ATF before oiling and installing everything iirc.

[ealoken]

0.7mm? Seems very high, I think that will cause a blow by = oil.

[four0four]

see here: https://www.us.mahle.com/media/usa/moto ... ions-2.pdf

I did want to err on the wider side, but this doesn't seem too terribly far off other recommendations.