While at it with engine rebuild question (1 Viewer)

[bmw635]

I've rebuilt and customized 2 Bmw engines so when I torn this engine down, I was surprised to see the condition . I've seen post of people rebuilding their engines claiming nothing worn and reusing everything until I saw this myself- Effing UNBELIEVABLE!

Given the cylinder wall condition with 275k miles wear on the cylinder wall and possibly some kind of coating that helps protect the wear, I just replaced OEM rings without honing or ring seating since the rings seem to wear may be 40% compare to new OEM ring. Some BMW engine have silicone coating on the cylinder wall so if you bore/ hone that, the engine is less durable.

The head was resurface, valve seat grind, new stem seal and reshim ( all shims were reused as it was within specs.)

All cam, crank, rod bearings were reused since no scoring, no slop so shy bother? Also, rod bearing and bushing are sold with rod only which was $600 more that I didn't want to spend.

 

[landtank]

if you still have the old HG would you mind measuring it's thickness for me?

thanks

 

[bmw635]

Sorry, HG is in the trash.

I can say that the HG material seems to stick to the block and head so only about 60-70% of the HG material was left on the gasket itself. There was about 1/16" of residue on the block that we had to scrape off and clean.

I suspect it melted due to hotter engine operating temp and inferior material. Cars use to run 80C/ 160F only and the hotter temp tends to break down quicker. I suspect the HG failure is result of extreme heat rather than design issue.

This is the 1FE-FZ t-stat info:
Engine temp A/C cutout spec = 226F
Thermostat opening temp spec = 180F
Thermostat fully open temp spec = 203F --- Ideal closed loop engine temperature

 

[Dissent]

So you reused the factory rings And pistons? Did you have the block cleaned, decked or anything?

 

[murf]

Have those injectors rebuilt while you're there...

 

[bmw635]

Head was rebuilt, block only got new rings, everything else was reused since we couldn't see the wear. We bought the rings and old rings seems to wear only 30% compare to new but since it's worn and we have the rings, we replaced it while at it.

Block was sonic test and checked, no decking needed so we reinstall everything else

Injectors were sonic cleaned since it's an easy change if there's any issue .

 

[BillyGoatMTB]

Bump

I have everything torn down to the block, the head's back from the shop resurfaced with a valve job and I'm ready for reassembly.

I think I'm going to go ahead and pull the oil pans and timing chain cover to replace the timing chain and guides to be safe.

I read through this post the rings were replaced without honing the cylinders? Is this normal that everything work out okay?

With as close as I am I'm tempted to just pull the block and go for it.

However, I thought my cylinder walls looked amazing and this is the reason I've been thinking about leaving it alone combined with my Blackstone oil reports for a few years showing no bearing wear..

Any thoughts?

 

[Emerald80]

I’m having a similar dilemma. Just pulled the engine in my 2nd cruiser with 356k miles due to a small head gasket leak and after tearing it down I’m amazed with how good the bearings, crank, pistons and bores look. Compression was 180 in all cylinders and oil pressure was good. I’m tempted to just put everything back together with new timing chain and guides after the head gets back and run it. I’m curious if just putting new rings in without honing worked out for the OP.