1992 VW Jetta GL
1.8L SOHC
3 speed automatic
136k miles

My girlfriend''s car has been having a string of bad luck.
A few months ago we took it in for a coolant leak, only to find
the radiator is plugged. See previous string of bad water pumps and cracked thermostat sensor housings.
Found out the temp sensor wasn''t detecting the engine over heating (nor the gauge) and no water
was flowing to the radiator. Bad. They replaced a lot of cooling system parts,
new timing belt, oil change, new PVC valve & hose, new valve cover gasket (top end cleaned up), tune up. Ran like a top.
They mentioned the valves needed adjustment, but this type needed shims and was beyond
their capacity to tune.

The temp gauge on this car almost never goes above 0, which is weird. Recently it sat in the exhaust repair shop running for about 30min
and when I drove it away it was quite hot (1/4 temp gauge) but cooled down quickly.

Car developed a miss at stop to acceleration after about a month.
A little fuel system cleaner and that went away.

Now it has a rough idle but runs at higher rpms quite fine.
Has a random ''cough'' that shakes the car at idle. And when she pulled in today,
squeaking at idle (belts are new).

Yesterday I put new wipers on, then decided to check the oil.

Noticed a bit of coolant on the block below cyls 3 & 4. But not coming from the hoses
or hot water out plumbing. Coolant fill bottle reading about 2" low.

Uh oh, LOW oil. Removed the oil filler cap.

WHITE GOO.

appears to be a mixture of oil and coolant (can see green liquids). Like green mayonase.
No wonder the valves are sounding bad.

Drained the (low) oil pan, looked good, no water, no white goo.
Just a tiny bit of white goo on the oil dip stick.

My guess is it''s a blown head gasket. A compression test should show which cylinder is bad.
I ran the test a few times on each.

#1 190 200 205 ( belt side )
#2 180 185 195
#3 195 200
#4 190 190 (transaxle side)

Wow no real good indication of a bad cylinder. Chiltons said 189 was the compression spec for this engine. But I haven''t found
any other good list of compression specs for this motor, so maybe they''re wrong? So....why am I reading higher?
Previous mechanic mentioned carbon buildup. Would that cause high compression?

Does this indicate it''s not the head gasket but a cracked water jacket - perhaps a cracked block - from the overheating
earlier?

Is it worth pulling the heads or should I take this car to the scrapper?
She''s convinced a new/used car will stop the $500/every 2 months repair bills that have been happening.
How much is a new engine?
How much is a head job?

I''ll be calling mechanics tomorrow but wanted some advice before I get fleeced.

The car gets 21-23mpg and is around town only (commuter).

Thanks for any advice,
-Zetan

If the car is never driven on the open highway where it can get up to 50 mph for at least 30 minutes - the oil isnt going to get fully warm. So the water vapor that gets blown into the oil around the piston rings wont get boiled back into vapor and out the exhaust. It will collect in the cool parts of the engine, as a sort of milk-chocolate milkshake consistency. The top of the engine - cam cover - is one of the coolest parts of the motor. Since you live where its chilly and damp - this is normal, and more noticeable in winter. You may indeed have a head gasket leak that is just starting, but with those compression readings - its not bad yet. Another way to check for a blow headgasket is to look at the radiator cap, to see if there is any oil scum building up. That would be oil from the engine getting pumped into the cooling system. If the coolant looks clean - dont go taking the head off yet.
While its possible to have a cracked block, a head that is warped or has a crack is about 100 times more likely. I would think a rebuilt head would be about $300. You could check prices for 'jetta cylinder head' at www.ebay.com. I would think the labor to install it would be about $200 to $300; but remember, there is usually something else needed along with the new head; or at least things worth fixing because they are easier to reach with the engine head out of the car. (The starter on my 1990 Jetta is one !!bleeping!! example).
As for a new or newer used car: She should check what the payments & nisurance would be; and if you have a loan to buy the car, be sure to figure the cost of the comprehensive insurance the lender will require. $500 each month or two may be cheap compared with a new car or one new enough to have no big mechanical problems for a couple of years. Personally, I prefer to spend my money on parts for the old car. I already own a big set of tools, so I do my own work.
One reason for your compression readings being higher than the ones in the manual could be that compression pressure gauges dont have to be very accurate. The important feature is consistency, and showing up a cylinder whose comp. press. is like 50, or zero.
And you need to get the temperature gauge to work right!

Thanks for your input!

There is no radiator cap. Seems the only way to fill this one is via the radiator coolant bubble on the firewall?

Here's a pic of the oil filler cap

http://skylab.org/%7Ezetan/media/goo.jpg

True about the radiator cap - but that 'pressurized bubble' is where you would see the scummy mess, if oil were getting into the coolant. The oily scum is lighter than the coolant, so will find its way to where there is a water/air surface. Sorry to have to say, the amount of muck on the bottom of the oil filler cap in your photo appears to be more than would happen - if the head gasket was intact. Depending on where the head gasket is leaking, or where a crack in the head might be located, there may not be oil getting into the coolant....yet.
I have a car (87 Dodge Omni) that got overheated and began using coolant very slowly. We drove it for another 5000 miles, about a year's use - before the head gasket got bad enough that I had to install a rebuilt engine head. For the last couple of months before the gasket blew out, we had to fill the radiator each morning; and just on local 'grocery store trips' it would take about a quart each day. By that time, coolant would flow up and out of the radiator if we started it with the cap loose.
Its been another year since I replaced the engine head, and we hope to get a few more years use out of the car.

Here's a good read about your problem.
http://www.offroaders.com/tech/milky-stuff-under-oil-cap.htm
Franco