Engine Rebuild Advice - To Remove The Head Or Not?

[Albertan]

You can't machine the crank. You will remove the hardened surface. Plus you can't buy oversized bearings. I bought a good used crank and a couple of used rods and re assembled my engine. Oh yes, getting rings was difficult as well. I ended up buying "Grant" rings from ebay. "Grant" is a known name. BMW rings were stupid expensive. If I had a do over I would go for a Lang crank and rods, wider bearings that won't crap out plus you are buying everything all together.

[digger]

You can't machine the crank. You will remove the hardened surface. Plus you can't buy oversized bearings. I bought a good used crank and a couple of used rods and re assembled my engine. Oh yes, getting rings was difficult as well. I ended up buying "Grant" rings from ebay. "Grant" is a known name. BMW rings were stupid expensive. If I had a do over I would go for a Lang crank and rods, wider bearings that won't crap out plus you are buying everything all together.

you can grind the crank and buy +0.25mm bearings

[Syfon]

You can't machine the crank. You will remove the hardened surface. Plus you can't buy oversized bearings. I bought a good used crank and a couple of used rods and re assembled my engine. Oh yes, getting rings was difficult as well. I ended up buying "Grant" rings from ebay. "Grant" is a known name. BMW rings were stupid expensive. If I had a do over I would go for a Lang crank and rods, wider bearings that won't crap out plus you are buying everything all together.

This is incorrect. You can machine the crank and it does not remove the hardened surface. Machining removes less metal relative to the depth which shot-peening & nitride hardening penetrates.

ACL sell over-sized rod & main bearings for the S54.

I'll have the crank machined and go with the relevant oversized bearings.

I do hear what you're saying re the Lang crank/rods but given the current exchange rate and how expensive it is, i'm not prepared to drop $10k aud on a Lang crank and other items.

My understanding is the head needs to be re-surfaced to ensure the head/block form a perfect seal?

Is there any other important info I need to know?

[Apex_80]

About to take apart an engine I picked up. Was told two cyinder walls are scored a little, How badly deterines which direction I go with it. I feel like having the block worked on opens up a can of worms.

[Syfon]

About to take apart an engine I picked up. Was told two cyinder walls are scored a little, How badly deterines which direction I go with it. I feel like having the block worked on opens up a can of worms.

Luckily for me the cylinder walls in my block are perfect.

But yeh, now that the head is off, there's a heap of other work to do!

[Apex_80]

Luckily for me the cylinder walls in my block are perfect.

But yeh, now that the head is off, there's a heap of other work to do!

What have you decided to do with it?

[Syfon]

What have you decided to do with it?

Keeping the stock pistons/rods, replacing rod #3 obviouisly.

Block & head going to the engine shop soon, a used rod/cap is on the way (everything will be balanced), bearings/HG/seals/etc. will be ordered soon and re-assembly will begin.

[bigjae46]

Oversized bearings are NOT for situations where you spun a bearing, machine the crank and now have a smaller journal. Oversized bearings are used to account for manufacturing tolerances.

If you removing material...it needs to be heat treated. If you don't the rebuild won't last long. The reason a Lang Racing crank is $700 is the heat treating. Had 2 machine shops confirm this...they work on airplane motors.

[Albertan]

Oversized bearings are NOT for situations where you spun a bearing, machine the crank and now have a smaller journal. Oversized bearings are used to account for manufacturing tolerances.

If you removing material...it needs to be heat treated. If you don't the rebuild won't last long. The reason a Lang Racing crank is $700 is the heat treating. Had 2 machine shops confirm this...they work on airplane motors.

Yep, I was just going to say the same thing. I do have a nice used crank with one oval journal. There is a local company that is doing a plasma coating to build up surfaces mostly for the oil patch. I was going to see if they would be able to restore the one bad journal I have. (Just for research purposes)

[Syfon]

Block, head, rods/pistons, crank, oil pump + cooler + filter housing all went to the machine shop a few days ago. Everything will come back clean, machined and ready to go. ACL Race bearings & ARP rod bolts tol be provided. They'll provide all the relevant measurements then it's re-assembly time. I'm also waiting on a shitload of parts too lol

[Arith2]

Those pistons have a decent amount of carbon on them. My engine that blew had comparable amount but my new one has much less. Whatever was contributing to the carbon may have been the cause of the wear. Just a thought because this is a lot of effort and money. It's super fulfilling when you get her running again. Good luck with everything. I'd love to see the start up video.

[Syfon]

Those pistons have a decent amount of carbon on them. My engine that blew had comparable amount but my new one has much less. Whatever was contributing to the carbon may have been the cause of the wear. Just a thought because this is a lot of effort and money. It's super fulfilling when you get her running again. Good luck with everything. I'd love to see the start up video.

Piston 2 did have a broken bottom ring. Who knows if this has anything to do with it.

I agree. This rebuild is running me close to, if not more than 5 figures. But I guess I'll have a brand new motor aha

[x Spades x]

Liquid Moly is the WORST. Everytime I put that shit in my engine, the oil temps go almost to the 3/4 dot (when hard street driving). That ridiculous... tried on two separate occassions... drained it in 100 miles... never again for ANY car

[Syfon]

Liquid Moly is the WORST. Everytime I put that shit in my engine, the oil temps go almost to the 3/4 dot (when hard street driving). That ridiculous... tried on two separate occassions... drained it in 100 miles... never again for ANY car

Something must be off with your motor/oil cooler/something else.

I've run it for 40k km. During hard street driving oil temps never exceed ~110c. On the track after a solid 10minutes of pushing the car hard, oil temps reached 125c (which is dead on 3/4).

In comparison, I had run castrol tws and that ran a little warmer, maybe by 5c (i.e. when cruising and when driving hard).

[Kdubski]

Do the headgasket. I had the opposite situation of you, my headgasket failed between cylinders (low compression on 4-5-6) so I took the motor out, did rod bearings, fresh gaskets, and of course head gasket.