On my way home yesterday I got the message "restricted performance". It seemed to drive normally and I was one mile from my house when I got a CEL and stalled. Had to be towed home. Upon examination, I had codes for both knock sensors, and coolant level was very low. I added water which leaked out towards the back of the engine, right side almost as fast as I could pour it in. I surmised it was a coolant hose underneath the supercharger. I removed the supercharger this morning (no small feat that) as well as an alarming number of other pieces that had to come off to get the supercharger out. There was indeed a hole in the right hand hose. During the removal I managed to break off a T-fitting on the left hose as well. The knock sensors are now accessible, but before spending a bunch of money I'd like to determine if any catastrophic damage has occurred.

When it stalled I coasted off the road and raised the hood. Some smoke was coming off the engine and I could tell it was very hot. The electric fans didn't seem to be running. The dash temperature gauge had not moved off the "normal" reading, although I understand the engine can overheat quite a bit before the gauge finally moves north.

So what's the best way to tell if my engine is a goner? Thanks for any advice.

Royce

 

I would suggest doing a compression test on all cylinders.

Will not be conclusive however if there is significant warpage it will show up. Very minor warpage maybe not.

Also if you plug up all hoses and put the cooling system under sustained pressure that might indicate whether or not there is a gap between the cylinder heads and block which is the issue with overheating which causes things to warp. So long as there are no other leaks that is.

 

i think you caught it in time, i would fix hose and drive around close to home and see how it preforms

 

the gauge moves off the middle at 115-120C, not really that hot. you caught it

 

These engines despite being aluminum actually have quite a bit of resistance to overheating or at least overheating damage. I once had an XJ8 go in the red while I was stuck in stop and go traffic. I blasted the heat and pulled over as soon as I could (about 1/4 to 1/2 mile) and nothing was leaking or steaming, apparently the cooling fan fuse had blown. I had the car towed and changed the fuse, oil and coolant and it fired right up, no issues or leaks for 30K+ miles.

 

But at this point, its apart and he's got to "spend a bunch of money" to put it back together before he can drive it. I like the idea of doing a compression test. But I think first, I would remove all the plugs and slowly turn the motor over by hand in the correct direction (don't turn it backwards) to listen and feel for anything hanging up or grinding or scraping. If it seems OK, then do the compression test. Next, I would fix just the broken coolant fitting and hose and do a cooling system pressure test to see if it will hold pressure. If you don't have the stuff, see if your local Autozone has the tools to loan (you actually buy them, but get your money back upon return). If both are OK, then I'd go into the "spend a bunch of money" mode and replace ALL of the plastic and rubber cooling system hoses, tubes and fittings because the nitrile has all gone soft and the PA66 nylon is all brittle at this age. Good luck.

 

Thanks for the responses. I've decided to take the spark plugs out and do a compression test. I'm feeling more optimistic now. Assuming compression is ok, I will replace the knock sensors and as many hoses as I can. Also clean the throttle body and change the supercharger oil , etc. while things are out.

 

There are two types of knock sensors, for early and later models, which are not interchangeable. You will need the top one on the diagram below.