So, yesterday after driving around town in LA, its been a bit warm, i went and parked the wagon, and was sitting for about 10 seconds, engine OFF. The very short black rubber coolant line, ( about 3 inches) that sits on the back left corner of the motor, decides to rupture and spew all my coolant into the street. I think i would have noticed if the temp gauge was high as i tend to watch stuff like that, BUT i cant say 100% or not if it was showing high temps. But i doubt it was.

Fast forward next day, i replace the hose and refill with MOSTLY pure coolant ( planning on adding as much water as coolant, but it filled quicker than i thought) I did add water, but maybe only 10% of the coolant that i added. Not sure if that was a huge deal. Either way, after i watched it idle for about 10 min, i check the gauge and it is pegged in the red, so i shut it off to cool down with fan running.

A bit later i test drive for first time, hoping it just needed more air flow and to get the coolant circulating, but after about a mile its in the red again.

So, just looking for basic troubleshooting here...

The radiator is relatively new ( replaced a year or so ago )
Headgasket and entire head/ valve jog done about a year ago, so lots of new stuff there, but seems inconsequential.

Could it be as simple as a shot T stat?

Thanks for any help !

- Grae

 

how's the seal on the reservoir cap or the whole reservoir condition ? if you loose pressure there it causes the overheating problem

 

Best thing to do is to pressurize system to one bar (~ 15 psi) when the engine is cold and see if it holds pressure for 10-12 hours or more. If it doesn't, find the leaks (hint: if pressure went down but you don't see any external leaks, pull the spark plugs before you try cranking it over..).

Yes, it could be as simple as a stuck closed thermostat. And yes, you should pressure ck the cap too, but that won't make it overheat except in extreme conditions (e.g. crossing the desert..).

Also adding more than 50:50 ratio of coolant:water will make it run hotter too. If you're in an area where ambient temperatures run hot (and you don't need to worry about freezing weather), you can get away with about 20-30% coolant to water ratio; will actually cool better.

But if it is overheating quickly, you likely have a stuck therm, or blown headgasket (let's hope for the former!).

 

If it overheated you should replace the thermostat anyway so it's a good place to start.

 

Did you loose any more coolant? My guess would be that you have a broken water pump. And if the temp gauge got into the red, you likely have a blown head gasket now. Pull the plugs and see if any of them are wet with coolant.

 

This is a water pump that I pulled from a 960.

 

It's rare to have the impeller fall off but it's always possible. If you start it up and get the temperature gauge starting to go up turn on the heater and see if the heat stays hot. If the pumps broken like in the picture the coolant isn't circulating and you won't feel hot air after a moment or two as the static coolant sitting in the core won't be able to keep heating air.

Also if the temp gauge is rising fell the upper hose as close to the engine as possible. If it's at the 3 o clock position or higher that hose should be hot enough you can't hold it unless the thermostat is stuck. If you fell it's not hot enough compared to the gauge than it's reasonable the thermostat is bad.

 

Nice tips.

I would like to know of a way to test the impeller for being off. Example, if the impeller is good, and I pull the thermostat, then start the car with the thermostat out, will it pump coolant out of the housing? I guess I can try it. But your way seems reasonable.

 

That impeller dropping off is rare but yes, if you pull the thermostat, start the car and water doesn't start pumping out the thermostat hole you do have a detached impeller. I have also seen where the impeller blades have worn down so it won't move enough coolant to allow proper cooling. It's usually due to running straight water or a contaminated mix and the blades actually corrode or dissolve away. That and the pump losing one or two blades usually because something entered the pump and jammed it for a second. Those are harder to diagnose as you pretty much have to pull the pump and inspect to see it.

I'm a big believer in adding an anti rust additive to the system every couple years between flushes. It's cheap insurance and it replaces the additives that wear out in the coolant without having to pay 30+ bucks for new antifreeze as the antifreeze part doesn't wear out.

 

Sorry for delayed responses-

After reading all that i just want to go back and re-state ( NOT that im disagreeing but just FYI ) headgasket was done less than a year ago, with that a brand new H20 pump among other things. So i see i see it unlikely, but of course anything is possible.

That said, Yes, i noticed that the cap has some pressure cracks in it, and the car has been very slowly running low on coolant over the last bit.

Let say for the moment im running 90% coolant, and 10% water... Could these two issues combined cause it to overheat?

When i noticed it first, it was sitting idling in 75 degree weather for a good 10-15 minutes. ( cause i was watching for leaks... Had no thought to see if it would overheat, since it hadn't been overheating the day the rubber hose popped)

For now im thinking i will drain some of the coolant, add more water and check some of the other items you all mentioned. Also, order a new cap and T stat for good measure.

Will update !

Thanks!

- Grae

 

Quick update, Went to start working on it again, and the resivour was empty, so i added fresh water. Drove it around the block a few times and it stayed at mid temp, and ran great. I parked it and let it idle and thats when the temp began to rise. I felt the upper coolant hose that comes from the t stat, and it was not hot at all, very comfortable to hold with my bare hand. So im def siding on the T stat, and hopefully that an easy fix. Il pick one up today and see what happens.

Also, i ordered a new expansion tank and cap from IPD, just to cover my bases. The old tank was grimey anyway. LOL

 

The thermostat is an easy job.

When we had a head gasket problem it slowly got worse and worse over a 2 year period. When I pulled the head I realized that the head had been done within 4 years. Which means that there is a high possibility that something wasn't done "JUST RIGHT".

Loosing coolant is NOT good. We were loosing it through the cap. You adding straight coolant, 1 gallon would not have put you to 90/10 but more like 75/25 which I doubt would cause you over heat because of the mix.
Head Removal and Installation, Volvo 850 / S70 Turbo B5234T, B5254T, Head gasket replacement, valve replacement.

Personally I believe these heads are so soft that they are unforgiving to overheats. Just 1 overheat can cause a breach in the head gasket.

Is the fan coming on?

 

 

I'm with Robert. The mix being strong on antifreeze if anything will allow higher temperatures before boiling but shouldn't be any reason for it to overheat.
That said I'd still bring it down to a more normal 50/50 when you get a chance.

As before, I'd recommend doing the thermostat even if it was new when you did the head gasket as it has been overheated since. And although it doesn't always happen, overheating a thermostat can kill them.

 

Oh, and NEVER add tap water unless you are about to totally flush the system.

 

As in tap water, like "hose water" ? LOL... cause i always do that :-/

BUT, seems to be back to normal with a new T stat installed. The upper elbow is now very hot to the touch and the motor seems to not be overheating, with the exact same drive and idle time as i did this morning.

Im going to keep an eye on it, but i think were in the clear!

Question though, as i was shopping for a t stat on line, i kept seeing things in the 90 degee range. When i ended up at my local parts store and they offered me a 175 degree. Is this just a metric to standard conversion issue? They couldn't possible have that much range!

 

They have thermostats from 160 to 195 for most cars.

There is a difference in the stock temp between the turbo and the NA. I think it's 8 or 10 degrees ??

I've always thought if you had a cooling problem you had a problem you needed to cure. I've never looked at the thermostat by itself as a cure. After all a colder thermostat only opens sooner. It doesn't keep it from overheating it only allows the fan to help out sooner. Whatever problem you have is still going to push the temperature over the top. At least that's how I look at it.

Glad to hear the thermostat might be all you need !!

 

The Whaler t-stat is the best. I usually get the 90 degree one, that starts opening at about 184 and is fully open at about 194. I think 175 is to low. When my car hangs up at 175 I immediately replace the thermostat. The fan won't kick on until about 216. Has the fan been kicking on?

I think the car will run rich at 175.

 

There are two thermostats for those cars 87 or 90 celcius.......the one you bought was in farenheit... 87 is equal to 190... and 90 is equal to 195

 

In hindsight I would deduct that the day your car first overheated was the day that your thermostat failed. Causing the turbo coolant line to burst, since it was the weakest link in the system, most likely due to it's age and location behind the engine near the exhaust manifold.