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Hi,
What a revolt in’ development this is? Are you having a “Life Of Riley” moment? 😳
Shame you didn’t try the heater/blower trick before ordering a radiator.
The clean spark plug and low compression is kinda of a late check up. I was thinking you said you did that along with lots of other possibles.
Within that you are saying that you had no clues for it.
Like the little thicker or wetter accumulation behind the tailpipe is can be a definite tell. Yet no noticeable loss of coolant or Rusty water?
I would not be so concerned about machining the head but look out for corrosion.
On it or the engine block as it probably got under the head gasket a tiny bit. You mentioned a rust condition.
I will be surprised if you need to flatten the head or work on the valves since it appears you have caught this early.
The valves should be OK as it was running fine just before.
Once you get the head off turn it upside down and fill the combustion chambers with water.
Cover the valves tulips to see results out the ports on either side.
If you lose water right away then you may have a warped valve but it’s very early in the game for that to happen.
Even a burnt valve takes a lot of time to develop.
You never overheated so what I’m hearing you only steam cleaned that #2 cylinder temporarily.
How many miles are on the rings as the compression just seems normal too me. You just need a head gaskets all around.
In old days… redoing the valves only prompted a myth, that it adds more pressure onto the rings and then the rings get worse and it will use more oil.
I don’t know if I even believe that.
It was more an excuse to get a person to do a total rebuild or later. to be use as a scapegoat out of any warranty for the engine work.
Blow by is blow by and there just might be a little more of it if the valves were truly leaking.
The Volvo head is a nice piece of precision and that they run as long as they do.
Seldom do you hear about bad valves unless the engine had deteriorated from the lack of some good maintenance.
No Tuneups or abusive driving make bad valves.
Turbo boosting is another story.
You might want to for go the head work altogether, if it’s less than .020 out from corner to corner.
It may be half of that as being normal.
There is going to be some but it’s usually minimal and the reason for the specification.
Anything less is what the head gasket is for.
You have to remember that you are checking for flatness while the head is in a relaxed state.
The heating and cooling of the head over the years cause internal stresses to appear. They are usually minimal because the casted head is annealed before final machining.
So, at this point it’s will be stress affecting the cam journals alignments.
If you have it machined they will have to be aware of the cams journals alignment and ask about what they do about it. I’d like to know!
Just a precautionary thought, I have on my own, about resurfacing a head of aluminum or iron.
I have never read this about anyplace but then again, I don’t claim to be an automotive machinist.
Maybe that’s why they read for flatness corner to corner. It’s the hump or valley in the middle I’m concerned about. They do not use Babbitt inserts to exchange out using Plastigage, like on crankshafts.
If it gets decked there is a minimum dimension, from the journals to the deck called out in the specifications sections of manuals.
Why I don’t know exactly since the cam turning is done by a belt. So it must be valve clearances down to the top of the pistons as they will be lower overall.
In the case you must scrap the head or dish the pistons out slightly and that would be questionable as having to allow for carbon deposits I bet! 🫣
As I remember the specifications are only for the amount of warpage allowed plus ???
Don’t do it unless you have too.
It’s similar to brake rotors, except the thinner they get, the more often they will warp again sooner.
There, you change stopping habits or keep good coolant in the engine block for the head.
It was proven that Metal to metal seams never work but designing helps more.
I heard that the British tried the experiment with Rolls Royce’s or Bentley’s in their early years to make a gasket-less engine.
Maybe it was around the thirties or fifties?
Maybe other another brands of British, I don’t really know.
But they wanted certain retail customers to begin with.
Everything was totally hand lapped and fitted so precisely that it created other problems.
It was touted in sales on production models to have the hoods sealed or wired down so that only their technicians worked on them or void the warranty.
Some elite road service that would be.
If these vehicles ever got to venture out on the open roads from a pampered home life of Europe.
So if it is true, nobody would know but those in-house mechanics.
Maybe it’s all fictitious?
I’ll write this up as American or German propaganda to old and some younger rich men to buy domestic.
My economics had me give up on Ford and Chevy P 30s. 70’s and 80’s were junk.
The Volvo 240s rescued me. Beat car payments or lasting 11 to 17 years was an understatement.
So, Just saying be careful with whom you let do the resurfacing.
I have heard the term “broaching” before in one automotive machine shop that made me question their skills.🤔
It is a term they used for their head resurfacing machine.
I didn’t get to look at it so I walked away.
For me, a broach is a tool used to cut internal slotted keyways in a through hole using an arbor or hydraulic press with sized sleeves with shims.
Examples of internal cuts are a hub of a gear, sprocket or crankshaft pulley.
A broach or the Broaching term is the movement of a single edge cutter but edges in multiple successions with graduated feed or depth control.
So rotating many cutters on a rotating head might qualify technically as the same thing. 🤔
I had better leave that one alone on a forum.
I need to ask if you ever saw a lot of oil sweating above the oil filter from under the head.
Hard to see on a turbo but that is a sign of a head gasket leak too.
There is a pressurized oil galley right up to the head there.
So is Number Two Cylinder?
Phil
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