1992 jetta 8v lost coolant and died?

I was sitting at a stoplight, and the car was at normal temp according to the gauge, and it suddenly blew the blue coolant temp sensor out and started running really rough. I couldnt just shut it off because I was in the middle of a busy road facing up hill so I had to drive it off the road, and by that time it would barely move even while cranking the starter. I put the coolant temp sensor back in and filled it up with water, but it still wont stay running. Any ideas? Also, i want to check the compression, and pull the fuel pump relay before doing so. But, it looks like you have to pull the center console, both underdash panels and the knee bolster to even see which relay it is. Is it really that complicated to do such a simple thing? lol

Head gasket pressurizing the system?

hard to say, but a compression test is a good start. I don't have a wiring diagram in front of me, but there should be a fuse in the fuse box for the fuel pump. Any chance you have the owners manual? That would have a fuse listing..

Its relay 18 according to the diagram, but its the later one with the knee bolsters, and the relays are right up against it so you cant see the numbers and im not familiar enough with it to find the right relay by feel.

I figured out which relay it was and checked the compression, its 170-120-120-170. Not great, but shouldnt it still start with those numbers?

Is that new enough to have one of the water pumps that looses the plastic impeller off the back? You might want to check to make sure coolant is actually circulating.

In theory 120psi is enough to run on. But the fact that the two middle cylinders arte drastically lower tells me that there is a head gasket leak between cylinder 2 and 3. Notice any coolant in those cylinders while doing compression test? Did the piston tops in those cylinders look cleaner than the other two?

Between the coolant temp sensor coming out and the timing retarding due to detonation, it's not surprising for it to lose power and stall. You could try disconnecting the battery to clear the ECU and reset the ignition curve and try restart after that.

It wouldn't surprise me if the head gasket is blown, that car had the head replaced with another used one because it was burning a quart of oil every 200 miles because the valve guides were worn so bad. It probably has 70k miles since then though. It's my sisters car, and she just bought another golf (an aaz swapped syncro) so if this one is dead for a while I guess it's not that big a deal.

Meanwhile, I drove mine for something like 20 miles with the temp gauge on peg, and it's still fine...

I'd start by drying the ignition out. If the car was at normal temp, and some VW plastic failed, causing the thing to lose its coolant, you haven't really given it enough time to overheat. If the sensor was knocked out by a piston or valve smacking it on its way out of the engine...different story.

The ignition (at least the distributor and wires) didnt really get wet, the rest idk. It still doesnt seem to want to start anymore than it did yesterday tho.

In reply to Travis_K:

You don't have to take any of that stuff out. The fuse box is under the dash on the far left. The fuel pump relay is the silver one in the upper left corner. It looks like the hazard relay but it's smaller.

Here's how I know:

M030 wrote: In reply to Travis_K: You don't have to take any of that stuff out. The fuse box is under the dash on the far left. The fuel pump relay is the silver one in the upper left corner. It looks like the hazard relay but it's smaller.

That makes sense, its just hard to see the numbers. I looked at the golf (which is older and from germany) where you can actually see the fusebox, then I was able to figure it out.

Any update? Did you get it running?

Nope, I haven't done anything with it since I checked the compression, the only other thing I can think of is to try swapping the distributor, this car has gone though several already, so it might be worth trying. Other than that I have no idea, other than try to convince my sister to get rid of it lol.

I tried using starting fluid to see if the car might start for a few seconds that way, but nothing. My guess it that it didn't overheat, but something in the engine happened to pick that time to fail and vent cylinder pressure into the cooling system and blow the sensor out, now the whole engine is probably junk. For a car that the normal price for a non broken one is about $300 above the absolute worst condition vehicles that can still be legally driven under their own power on public roads, is it really worth fixing?

Where are you Travis? I know a sucker in Massachusetts who can't resist A2 chassis Volkswagens (me).

I'm in California. Even though my sister just got another car (a 87 golf syncro, which is more more rare/valuable), she refuses to even consider selling this one. Even though the rest of the car is in reasonably good shape, this car has given me the opinion that VWs (especially mk2s) are some of the worst cars ever made, although I know most of the ones other people have work fine. I did try swapping the distributor with another one (just because they have failed a number of times before), but that didn't help either. Other than the compression on the middle 2 cylinders being a little low there is no other good indication of mechanical problems, although when i did get it to start for a minute after if first died it looked like there was a puff of coolant steam out the the dipstick tube when it died again.