Rebuilding head questions/other options

[Jake325is]

I have a 220k+ mile m20 that is starting to show age. The compression test done about 10k miles ago was:
Cylinder 1: 130
Cylinder 2: 125
Cylinder 3: 120
Cylinder 4: 120
Cylinder 5: 115
Cylinder 6: 110

I have found a rebuilt cylinder head for a few hundred bucks, and wondering what all else I need to get to do the head rebuild. Also need to do the timing belt while I am in there.

Other option is to do a swap. There is a m60 with a few parts to do a e30 swap near me for 700, also looking at s50 swaps but have heard some say its not worth it... Need help on deciding what to do and what parts I would need for the m20 refresh, not trying to go all out, just want to get back to near stock.

[e30davie]

What guarantee is it that the rebuilt head you buy is actually rebuilt? If you are going to spend money on any head, pay the machinist yourself. You never know what you are gonna buy and how honest the seller is.

[87-325ic]

true words above.
i bought a rebuilt head here on the forums a loong time back, turns out it had chewed a valve in its lifetime, evidenced by lots on marks on the combustion chamber. they also used vice grips and a hammer to put the rocker shafts in. fucking idiot kid. i was too when i bought it though.

do the rebuild yourself. take it to a machine shop yourself.

also, what says your head is causing the low compression? have you ruled out good or bad rings and such?

[e30davie]

i spent almost $2k AUD ($1600 USD?)doing a top end rebuild on my M20.

Head machining - all new exhaust valve guides, skimmed, acid wash, valve grind.
-water pump
- timing belt kit
- all new front belts
- a few coolant pipes
- injector clean and all new injector seals
- all top end gaskets - full elring kit - quite expensive to buy the full kit
- rocker cover gaskets
- alot of new vacuum lines - some genuine - some DIY
- rotor and dizzy cap
- new spark plugs

Does it run beautifully? Yes.

[Jake325is]

-The shop that the car has been takin to since '94 that did the compression said it atleast had a leaking head gasket. The head for sale says it was done by a shop not far away so I thought about going and having it tested.
-And no I have not ruled those out. Trying to take all things into consideration. I live at college and have limited money and little to no places to work on car.
-And thank you for the list! My I did the cooling system not long ago so I am deciding whether I should wait another year or do it now!

[e30davie]

Assuming those compression results are in PSI they seem insanely low. Does it run good?

Is it showing any other symptoms of head gasket? overheating? water in oil? oil in water? water out the exhaust?

I suppose possible you have blown gasket through between 5 and 6 based on those numbers. I would expect the numbers to be drastically lower on 5 and 6 if that were the case.

Unless they did more tests than a comp test. Like a leak down test perhaps.

[noid]

Get a leakdown tester and do a leakdown test. It will tell you exactly where you are losing compression.

That way you dont go tossing a bunch of money into the head for no good reason.

[Jake325is]

Yes that is in PSI. No there is no water in the oil or coming out of exhaust. It does have a little heating issue when still, but I think that has to do with needing a new thermostat. Putting a new one in this spring.

And okay I will do the leakdown test as soon as I can.

Thanks for the help so far guys!

[MrBurgundy]

Get a leakdown tester and do a leakdown test. It will tell you exactly where you are losing compression.

That way you dont go tossing a bunch of money into the head for no good reason.