Head Gasket Leak

[ggunder]

My 1970 2000 engine was rebuilt about 2+ years ago. The head was below the allowed thickness, so the shop installed a copper head gasket that was thicker to make up the difference. Right away I was concerned that the head gasket was leaking since there was oil near the passenger side rear of the head as well as some minor coolant from various areas around the head. I watched it closely and monitored coolant levels as well as the condition of the oil. While it was losing a little coolant, the oil was always very clean.

Recently the car started running very rough so I pulled the plugs to inspect them. The #3 plug was oily and fouled (probably misfiring) and #2 looked oily as well. The #1 and #4 plugs looked just fine. So now I want to get this fixed once and for all. Oh, and also I think it is leaking oil from the rear main seal. So, what is the best course to take? Thank you for your input, I need to jump on this.

[K1200 GT]

Pull the engine and trans. start from scratch. If you are going to replace the seal. If not pull the head and see what you have.

Rich

[notoptoy]

First off I would take a compression check, that will tell you a lot. Do you see any oil in the water/radiator, how about water in the oil (milky white oil on the filler cap?)
If your compression check indicates problems, the next test would be a pressure test on the radiator to look for a bad head gasket or a leak-down test on the cylinders for bad head gasket, valves or broken rings.

While it is a relatively simple matter to pull the head and surface it - if there is enough material left - there may be other issues - did they deck the block when they did the rebuild?

Some say you can change the rear main seal with the engine in the car - I don't think it's worth it to try, it's so relatively simple to get the engine out as a unit it's just easier and much less frustration to go that route.

If the oil leak was always clean, I'd suspect a valve cover gasket before the head gasket at first shot.

[Linda]

Does the 2L have valve seals?If so maybe they are leaking.
Linda

[fj20spl311]

Sometimes the leak at the rear seal is caused by too much thrust clearance.

[K1200 GT]

When you say you have two cylinders side by side with fouled plugs. And coolant leaks from around the head that sounds like head gasket trouble to me. You could re torque the head put clean plugs in, do a compression check. But if you want to fix it right. I would pull the head. but thats just me. It doesnt have to be blowing coolant into the oil to be bad. IMHO

Richard

[notoptoy]

When you say you have two cylinders side by side with fouled plugs. And coolant leaks from around the head that sounds like head gasket trouble to me. You could re torque the head put clean plugs in, do a compression check. But if you want to fix it right. I would pull the head. but thats just me. It doesnt have to be blowing coolant into the oil to be bad. IMHO

Richard

Good catch Richard, for some reason when I read the original post I didn't register the reported coolant leaks! I'm pretty sure the head will have to come off regardless, but it is still good to run the checks to pinpoint the problem for the best repair(s). I think the harder decision is what to do about the leaking main seal - if the engine is going to come out, I hate to say it, but while he's there, he may as well have it all checked out (at the least I would consider putting fresh bearings on the crank since it's "open"). When it's out is a good time to check the clutch and address any Transmission anomalies as well.

Of course the budget, time and skills affect all of this.

[Linda]

Was the head retorqued after the rebuild and did they put all the bolts in the right place?

Linda

[sports imports]

Linda:
U20 heads have the same valve seals as the late model R16 head. The head bolts in U20 are 5 long and 5 short so mixing them up is impossible.

Retorquing the head bolts(Gary did you install studs?) costs nothing if it solves your oil leak.(unlikely but worth a try)

My guess is that the head needs to come off to determine if the thick head gasket has been compromised.

Ross

[ggunder]

Here are a few more items of note:

The head does have studs and I have retorqued the nuts.

The rear main seal was new when installed not long ago and they are a simple rope-style design that may be prone to leaks in any case. I don't want to "fix" it when the problem is the seal design and not the part or installation.

During the rebuild I got new pistons and all bearings, including a crank grind and main bearings.

I have seen a few small globules of oil in the coolant recovery tank.

The block was decked during the rebuild.

Thanks for your input, I am tempted to start pulling the head off right now!

[notoptoy]

If you have done all that you stated, then yep, time for the head to come off. You may need to search for a new head if this one can't be milled anymore.
As far as the rope seal, it is a poor design, but they can be installed with care and using a few tricks and not leak - one wrong move though, they will leak big time - believe me I know!
How bad is the leak? Mine was urinating oil at an obscene pace - and is the reason I have my block out and at the machine shop - a serious case of while I'm there!
Tom

[ggunder]

Tom,
The leak really is not that bad, and it is great because it gives my wife something to distract her from other things in the garage. Not only that, but if I get the head squared away, the leak will probably be reduced anyway. Now I have to read up on how to not mess up anything during the disassembly process.
Thanks again,
Gary

[K1200 GT]

ggunder,

I have a head, new seats/ no valves. I havent measured it. It came with an engine that I want just the crank and pistons. If you are interested or anyone PM me.

Richard

[ggunder]

Ok, to remove a 2000 head (w/SU carbs and alt. on passenger side):
1. Drain radiator (block too?) and disconnect radiator hoses
2. Remove air cleaner
3. Disconnect alternator from head
4. Disconnect throttle and choke cables, vacuum line to distributor
5. Remove intake w/carbs still attached?
6. Disconnect header pipe, leave it in place?
7. Remove valve cover and vent tube
8. Back off head nuts from studs (in any particular order?)
9. Do something with the timing chains?
9. Remove head from block and inspect?

Can I leave the thermostat attached to the head?
Probably better remove the spark plug wires and loosen up the spark plugs first.
Will the head really stick to the block? If it does are there any tricks to get it unstuck?
Should I set up the engine on TDC before starting?

Thanks for the advice,
Gary

[notoptoy]

You need to look at the service manual in the WIKI and follow the instrucations!! http://www.311s.org/PDFs/U20Eng_TrnServ ... nual40.pdf" onclick="window.open(this.href);return false; and http://www.311s.org/PDFs/SPL311ServiceManualSML.pdf" onclick="window.open(this.href);return false;

Yes, I would start set up at TDC on #1 cylinder.
Yes on #5 - that's how I do it anyway, and this also removes the exhaust manifold.
#6 depends on how tight your system is, if you can get away with pulling the exhaust manifold back the inch or so you need without disconnecting anything, I would. If it's really snug, or you don't want to take any chances, go ahead and remove the first joint on the exhaust.
The first #9 - VERY important, do this BEFORE #8 (See #1 above!!)
You can leave the thermostat - though you will probably take it out later.
Wires yes, spark plugs optional, now or after you have pulled head.
The head will likely stick a little bit, usually several well placed whacks with a rubber mallet will loosen it up