Valve bent, piston indents... :-(

[sapote]

It was more on initial torque down of cams. I felt resistance, but I was working through cam binding... so thought the resistance was due to this.

This makes sense, when the cam is out of timed with the crank. Regardless if the crank locking pin was in or not, if the piston at TDC it will bend the valves. Luckily this is a S54; if it is an M54 engine with aluminum block, you would have to add Timesert to all the threaded holes for the head bolts as the aluminum threads are not reliable after unbolted the head.

[Cubieman]

If you had the crank locked at TDC1 and the cams set up with the bridge you would be OK. But what is to keep the properly timed cams from spinning due to valve spring pressure when bolting them down creating this potential issue OP experienced?

[Icecream]

If you had the crank locked at TDC1 and the cams set up with the bridge you would be OK. But what is to keep the properly timed cams from spinning due to valve spring pressure when bolting them down creating this potential issue OP experienced?

I assume another wrench on the cam to hold it in position. I'm about to install my head too so now I am curious how to go about it without the cam tool. Maybe I just get the cam tool...

[Cubieman]

I assume another wrench on the cam to hold it in position. I'm about to install my head too so now I am curious how to go about it without the cam tool. Maybe I just get the cam tool...

Probably a good idea to go with the tool.

[DoubleSidedTape]

If you had the crank locked at TDC1 and the cams set up with the bridge you would be OK. But what is to keep the properly timed cams from spinning due to valve spring pressure when bolting them down creating this potential issue OP experienced?

The other pairs of valve springs. Each cam has one pair of valves open when Cyl 1 is at TDC. Those springs uncompressing would require another pair of springs to compress, and that’s not just going to happen on its own without you putting a force on the cam to rotate it.

[DoubleSidedTape]

I don’t actually understand how you did this. If you have Cyl 1 (and 6) at TDC, you are meant to have Cyl 2 intake and Cyl 3 exhaust valves pointing down. But you said that you were torquing the cam bolts? When did the rotation happen?

[George Hill]

Honest mistake, sorry this happened.

TIS will state when doing something like this you ALWAYS back the crank up 45*, this will lower all the TDC pistons enough to not have contact with valves in case of a misalignment like the OPs. Once everything is tightened turn the cams to the TDC position and THEN move the crank back to TDC.

*Edit, like others stated, knock the high spots of the piston with a file and run it. Be sure to catch the debris and honestly if the engine is on a stand turn it upside down while you do this.

[x Spades x]

Can I lap two exhaust valves from an old engine, if new valves aren't available?
Will they seal as well?

[sapote]

Can I lap two exhaust valves from an old engine, if new valves aren't available?
Will they seal as well?

I would.

[digger]

The valves and seats need to be mint before you can lap them as it’s a finishing process. So it depends on condition of parts you are working with

[sapote]

My wife ran her 325iT with no coolant and cracked the head twice. On both times I bought the used head on eBay and both heads had leaking valves from collecting debris/corroded on the valve seats (checked with gasoline in the combustion chamber) . I lapsed the valves and fixed the leak, without removing cams + springs + valves.

[Pavlo]

That’s a bad one. You should be able to smooth it out as it was constant force that did it and not an impact. I once did a head on a car that broke a T-Belt (2.0 VW) and the piston straight up disappeared while doing a wide open test drive. On an M54 on a lower output engine I’d say this is ok-ish, but on a 8k rpm Motorsport engine this is beyond my comfort level. I may have some stock used piston that you can have, will look.

[x Spades x]

Ok so trying to take out the bent valve and running into an issue. So the valve is stuck almost all of the way open (spring just about fully compressed). How do I get this out? Usually you can compress the spring enough to take out the keepers and tge retainer pops off and everything seperates. I guess the valve is bent higher up on the stem?.

[AdamM3]

So this where you need to use a lot of caution. Bending the valve back may damage/crack the end of the valve guide. The valve guide could already be damaged if the valve is stuck all the way open and the stem is bent that much. It's going to be tricky to remove the valve without damaging the guide. I knew someone that this happened to as well and the valve guides got damaged by bending the valved back enough to get the keepers off.

[x Spades x]

So this where you need to use a lot of caution. Bending the valve back may damage/crack the end of the valve guide. The valve guide could already be damaged if the valve is stuck all the way open and the stem is bent that much. It's going to be tricky to remove the valve without damaging the guide. I knew someone that this happened to as well and the valve guides got damaged by bending the valved back enough to get the keepers off.

Is my only option bending the valve from the bottom?
if I damage the valve guide, are they easily replaceable?