overheated 1998 S90, potential damage?

thefisch · Post by **thefisch** » 13 Jun 2021, 18:55

Car appears to be low on coolant and was driven while overheated for a few miles. Unfortunately the car is out of town (working on a tow to get it back home) so I don't have my hands on it yet. Going to drain and check condition of any remaining coolant, refill and pressure test for leaks. In addition to fixing the coolant leak, I wanted to ask the forum what else I should check for potential damage from the car overheating. Thanks in advance for any tips.

Here is what I know so far - family member was using our 1998 S90 out of town this weekend. Car was fine on the outgoing highway trip, and during some local driving at destination. But when they were about 3 miles from the hotel after dinner, they noted the CEL came on. Car was driving fine apparently so they kept going given the proximity to the hotel. Then with 2 miles left, they noted the water temp gauge started to fluctuate from cold to red but then stayed in the red. Thinking the thermostat might be broken, they finished the final 2 miles and when parked at hotel, they noticed some steam from under the hood.

This morning I had them check the coolant reservoir and it is completely empty. It was at the max line a week ago when I checked it and no signs of any leak before the trip. About a month ago, we replaced the heater core valve and the system pressure test was good afterwards. So I've been watching the coolant level closely and thought after a month that it would be good for a road trip. Oh well...

Post by **RickHaleParker** » 14 Jun 2021, 18:36

The 2.9L six cylinder is a long head. The longer the head the more prone it is to warpage. That one of the reasons they invented the V8. Two short 4 cylinder heads are less prone to warpage.

Compression test and do the chemical test for exhaust gases in the coolant.

thefisch · Post by **thefisch** » 15 Jun 2021, 07:47

Thanks Rick for the response.

Got the car back and there is a crack in the radiator tank near the upper hose. Doesn't appear to be any coolant left. Going to replace the radiator and also the hoses and thermostat for good measure.

Guess it's just old age - 23 year old plastic. It wasn't leaking at all prior to this trip and was pressure tested a month ago. Oh well - back luck I suppose.

As far as collateral damage, it may be too early to say. Car started up fine and sounds normal when idling and on a short drive off the tow truck and another short test drive when cold. No obvious signs of other leaks.

Post by **RickHaleParker** » 15 Jun 2021, 08:00

thefisch wrote: ↑15 Jun 2021, 07:47 It wasn't leaking at all prior to this trip and was pressure tested a month ago. Oh well - back luck I suppose.

It had your attention, liked it and wanted more.

thefisch · Post by **thefisch** » 15 Jun 2021, 08:06

Yeah, it has my attention and my wallet also. We replaced the front suspension two months ago which is when the heater core valve leak was spotted. In for a penny, in for a pound I guess. Cheaper than replacing it for sure given car prices right now.

thefisch · Post by **thefisch** » 16 Jun 2021, 15:21

The culprit is the radiator fan. It blew a fuse - replaced the fuse and it blew again. Looks like the fan motor seized. Getting a Dorman replacement.

So I suppose the sequence of events was the fan stops and next the pressure builds with the higher temp of the coolant. But instead of the coolant tank top blowing off to relieve the pressure (and save the radiator), the plastic on the radiator tank cracks. Just my good luck I guess.

Post by **volvolugnut** » 16 Jun 2021, 15:37

23 years of heat and pressure cycles is pretty good plastic radiator life.
volvolugnut

thefisch · Post by **thefisch** » 16 Jun 2021, 15:49

True, but if that cap had popped, it would be a lot less time and money.

thefisch · Post by **thefisch** » 10 Jul 2021, 14:38

Here are some pics of the old radiator for those interested...

thefisch · Post by **thefisch** » 10 Jul 2021, 14:46

Here are some pics of the replacement radiator. Only issue as the new fan housing didn't exactly line up flush with the shroud.