Waterguy

Started the car at 5:45 am this morning to go on the monthly PCA drive. It started firing on two cylinders, the remaining two caught after 15 seconds or so. I remember that the car had started this way last time I drove it (week ago.) Seemed like a lot of steam from exhaust condensation. By the time the car was fully warmed the steam hadn't fully cleared up, so I pulled over. It seemed that the exhaust had a sweet smell (antifreeze?) Back home we go.

Symptoms (or lack):

1. Coolant full, no oil in coolant, running just slightly hotter than usual.
2. No indication of water/coolant in oil.
3. Plugs look good (slight fouling), but deposits (mineral-like) on #1 and, to a lesser extent, #2.
4. Compression test results (warm): 153/149/149/151.

I am thinking head gasket, probably rotting around water passages due to age rather than "blown".

I have also had increasing oil consumption over the last year, increased from 1 litre per 1000-1200 miles to about 1 litre per 500 miles. (110k miles, btw.) When I parked it on a steep downhill, oil pooled in the cylinder(s) and I burnt blue for 2 minutes, otherwise no sign of smoke (cat works good.) All oil leaks attended to. Based on all the above, I am thinking valve guides/seals are due for replacement. Rod bearings done 1.5 years ago.

My question: Keep driving, do more diagnostics or pull head? If I pull the head, it will get a valve job (at a minimum) and the cylinder bores will be inspected/measured. What else should I do "while I am in there"?

I REALLY wanted to do the major work on this car in the winters so I could drive it in the summer!

Waterguy

Bump?

Charlotte944

Man, this is a tough one, but I'm leaning towards a head gasket.

I'm in the middle of my third head gasket (my first on a 951), and one thing that I would recommend is replacing the valve guides and seals when you get the head done. New guides run from $4.00 to $7.00 or so each. I put $4.00 guides in my '87 NA, and the 951 is getting more expensive (not sure why) guides from Pelican Parts.

I would really like to see pictures of your plugs.

dand86951

How long did you let it sit before the rough running on startup symptons show? You could let it sit again, then on startup, if it runs rough immediately shut it down, take the plugs out and see if any are wet with coolant.

Waterguy

The car sat for a week before the rough start symptoms showed up. I think I will try your idea today, although it has only sat for one day. Seems like the best idea I have heard yet.

Cliff, yes I will definitely have all valve guides replaced. What about lifters? I know I have a couple that are noisy on start-up, but I have never identified which ones they are.

Another question: What are the shop time/charges to re&re the head? I am torn between doing it myself and being able to address any other issues I find (maybe reseal the oil filter console, etc.) and having a shop do it so that I can get my car back on the road sooner. I assume the paarts and machining costs will be equivalent either way.

Thanks for the help so far.

Tom M'Guinn

When my HG went, I had a hard time diagnosing it. (I never had oil/water mixing.) While I was trying to figure it out, the problem became more and more obvious, until finally water started spitting out the tailpipe. You are better off not letting it get to that point of course. I'd try a leak down test -- or at least put some compressed air in a spark plug hole and see if the cooling system gets pressurized. Does it tend to run hotter under boost/load, and then cool back down if you baby it? That seems to be a HG trait. If it is the HG, don't be too intimidated to try it yourself. It is not that hard, and there are tons of people on this board who can answer questions.

Waterguy

Well I left the plugs out overnight and I now have a small amount of water (coolant) pooled in #1. That confirms it for me; the head is coming off.

I am not too intimidated about doing it myself Tom. Its just a matter of time; I have a trip planned for early August and it would likely be faster to have a shop pull & rebuild the head. I also would need to identify a local machine shop experienced with these heads and capable of doing a good job.

Danno

Count on 6-8 hours for a headgasket replacement. Most shops will charge you about $1000 for the job. Please take a close-up picture of where it failed in the #1 cylinder.

Waterguy

UPDATE:

The head is now off and in the machine shop. The head gasket was in PERFECT shape except near the water jacket on #1 and #4. On #1, there are a couple of small (1/4") holes that allow a little bit of coolant through the head gasket. The gasket material had rotted out and crumbled near these holes, allowing a small coolant leak into the compression chamber. Problem on #4 was similar but not as bad.

"While I am in there" the head is getting valves ground, all new valve guides and four new cam followers (hydraulic lifters.) Also resealing the oil cooler housing and air/oil separator.

Good news is that the cylinder bores look perfect after 110,000 miles. Damn, that Alusil is hard!

Danno

". On #1, there are a couple of small (1/4") holes that allow a little bit of coolant through the head gasket. The gasket material had rotted out and crumbled near these holes, allowing a small coolant leak into the compression chamber."

Hmmm, I'm not sure that would get any water into the combustion chamber. The fibre part of the gasket just separates flow in the head from flow in the block. With the holes rotting through, you just end up with more turbulent flow and perhaps not as efficient cooling. But for water to get from the fibre section of the gasket into the combustion chambers, it has to go through steel compression ring itself. Inspect that very carefully to see if there isn't a small pin-hole or a crack somewhere.

Another sign of a blown headgasket is a pressurized coolant expansion tank. It will get pressurized by the leaking gasket and push water up and out the overflow tube.

Just making sure that we're not missing something else that may be overlooked...

hosrom_951

Why don't you make the most of your head? replace the valves, guies, valve seats (ppl forget this), lifters.

If you HAVE got the times (an money) go for a head job like Lindsey stage 2. Port & police, valve cut etc.....at leats when you do so, you would be worry free and head performance mod free for next 10+ years or so.

Just a suggestion.

Charlotte944

I'm not sure about your area, but the shop I use here in Charlotte charges $168.00 to "check" a head. This includes disassembly, checking for warpage, broken springs, inspecting valve guides, and so forth. Things like stud removal and parts replacement are extra. For example, having the valve quides replaced was an additonal $20.00, but installing new valve seals is free.

The head from my 951 is in the shop for a "once over", new valve quides, and to have a broken exhaust stud removed. If all goes well I'll have it back this Wednesday.