How clean is clean

[Martijn 647]

Hi everyone,

 

I recently had a head rebuilt for the 1502 after I blew a head gasket and started burning coolant.

When I got the head back, I bolted it to the block, intending to use the multi-step method of torquing it down using angle measurements following a heat cycle. However, the car didn't start, life got in the way and it ended up sitting for about two months with coolant inside. When I again tried a start I immediately heard a loud bang and some smoke/vapor by the exhaust manifold. I assumed water had got into the cylinders so I removed the head to check. This was indeed the case. I checked the head and block for cracks/damage but I can't see anything. The valves look good too. Valve timing was also correct. I have no idea what the bang was, but I assume now it was coolant blowing past the head gasket. The head gasket was sold to me by the guy who did the head, it seemed low-tech, old, dry and perhaps NOS to me but I trusted the shop and went ahead and used it.

 

I am now again installing the head and want to make sure I am doing it as correctly as I can. I will be using the old method of torquing down the head, just in case I can't get the car to start for some reason, as well as using a new ajusa gasket. However, I am finding it really difficult to get the block as clean as last time. Attached are pictures of how clean it is right now. A rag, wooden sticks and brake cleaner just didn't remove much of the black residue, so I lightly used a scraper as well as scotch brite pad with brake cleaner, but I am afraid of taking too much material off the block. What do you think, is this clean enough? I can't really feel anything major sticking up from the block, but I'm also not 100% sure it is smooth enough. I am afraid the coolant somehow pitted the block and the grime is stuck in the pits. Right now taking the block out and decking it isn't really an option for me.

 

Any comments on my thought process are appreciated! This is my first head install and I just want to do it right.

[jgerock]

Clean out the head bolt cavities really well.

[Dudeland]

I would check the block to see if it is straight.  The markings look like there is some bridging between the combustion chamber and the cooling passages.  It looks a bit pitted.  Also there is some weird debris on the pistons, 2 and 3 look suspect. 

[Stevenc22]

If it feels smooth to the hand, send it. Some of the black might be staining in the top surface layer.

[Mike Self]

There appears to be some pitting around the edges of #1 and #2 cylinders, especially on the left quadrant (7-9 o'clock positions).  I'd make sure that wasn't too deep.

 

Also, M10 engines don't need angle torquing--just torque the head bolts down in the normal chriss-cross pattern (starting in the middle) at the torque specified in the shop manual.  

 

mike

[tech71]

4 hours ago, Martijn 647 said:

This is my first head install and I just want to do it right.

Then you need to check your block with a straight edge to determine if it needs to be surfaced, there is a good chance it does.

i see some noticeable pitting as well.

Mating a flat surface head to a not flat surface block is an exercise in futility.

I know thats not what you want to hear but there it is...

Edited May 31, 2023 by tech71

[Tommy]

To be 100% sure you would need to resurface the block but likely you'll be allright with a fresh gasket. I would try it before tearing out the bottom end just for that. Torque method, 3-step, is what I prefer (and re-torque after warm-up just for health of mind).

I have one old unused head gasket hanging on a wall that matches your description of the previous one. I wouldn't put that in an engine. It sure makes a difference compared to fresh one made of more advanced materials.

[TobyB]

Me no likey that discoloration around the 'downslope'

side of the block.  It looks as though it might be hiding something...

 

A flat block with sandpaper, used carefully, will tell you if there's too much pitting.

Be really careful to not let the edges dig channels, but the cast iron's pretty hard-

you're not going to remove 0.0005" even if you have at it.

 

I like the longboard method- the long sanding block for auto body, but with

any soft material removed, just the hard, flat metal surface.  

If it leaves puddles of unsanded surface, then having the block decked is worth it.

And not too hard nor expensive.

 

t

 

[tzei]

Fire ring(s) are not sealing enough imo.

[tech71]

So, does a 1502 take the same head gasket as  a 2L 2002?

Looks like whatever was on the block didn't line up correctly in places

And OP reported water intrusion into cylinders right after reinstalling the head.

Just checked, head gaskets have different PNs

11121734213    11129065653 

Got me wondering.... might explain some things

Edited June 1, 2023 by tech71

[tech71]

On 5/31/2023 at 3:40 AM, Martijn 647 said:

When I again tried a start I immediately heard a loud bang and some smoke/vapor by the exhaust manifold. I assumed water had got into the cylinders so I removed the head to check. This was indeed the case.

 

[Martijn 647]

Hi all thanks for the information, it gave me confidence to just go ahead and try, having the block decked will be an option in the future. I agree that the surface of the block could be better, I prepped it as much as I was comfortable with and decided to “send it”. Car started up nice, will retorque and keep an eye on the situation.  
 

@tech71 you are right, the gaskets are different. I’ve always used 1502 specific gaskets. 

[Tommy]

Let us know how it goes! The corner that tzei pointed out does look quite bad but, fingers crossed, you may get away with it.

[Dudeland]

16 hours ago, tzei said:

Fire ring(s) are not sealing enough imo.

That is what caught my eye, especially the one on the left.