1999 S80 T6 Overheating problem revisited

[chrism]

Some thoughts:

If you see "boiling" in the expansion tank even before the engine is fully up to operating temp, then it probably isn't really boiling, but rather air being pumped through the cooling system due to a blown head gasket. A compression test on all cylinders wouldn't be a bad idea in this case.

If it warms up to approximately the correct operating temp and the water actually starts boiling, then maybe you just have a bad coolant reservoir cap. If it doesn't hold the proper pressure then the coolant will boil at too low of a temp.

If you suspect a restricted radiator, you could disconnect both the upper and lower hoses and run a garden hose into the upper radiator neck. Unless you have some sort of super water flow out of your garden hose, the radiator should be able to flow the water through without backing up out of the upper neck.

[Riba]

Audis (& VWs) have changed since '86. Today's layouts will have the home mechanic's head spinning.

We owned a '79 Audi 5E in the 90s (5 cylinder North/South configuration with FWD) and we loved it. Very easy to work on and looking back on it don't know why I sold it. It was on its 2nd $300 fuel pump in under 2 years and at the time there were no online options. Big car that handled on rails.......

Yes, that the same engine I got, 2.3 inline 5 with Jetronic injection that is bulletproof. Mine is a GT Coupe (- Hey, is that a Quattro? - No, it just looks like one to an inexperienced eye. ) Back to the topic...

Give that sensor a change. Early on in my Volvo career I replaced an engine because of a coolant sensor.

Uh! That is a good tip. I will do that, can't wait to see what happens.

If you see "boiling" in the expansion tank even before the engine is fully up to operating temp, then it probably isn't really boiling, but rather air being pumped through the cooling system due to a blown head gasket. A compression test on all cylinders wouldn't be a bad idea in this case.

Nope, it boils when driven for a while, never when cold. Guess that is a good sign.

If it warms up to approximately the correct operating temp and the water actually starts boiling, then maybe you just have a bad coolant reservoir cap. If it doesn't hold the proper pressure then the coolant will boil at too low of a temp.

I replaced the expansion bottle but not the cap. Actually I got a number of them in the trunk as I suspect the previous owner went through them at some point. I don't think it is a cap but I might give it a try anyway. When it gets warm I can hear a very faint hissing from the cap but the coolant stays put. When I stop, the coolant level will raise until it reaches the cap, but it doesn't leak out. However when it boils it will raise and probably leak somewhere else as I have to add a bit afterwards.

If you suspect a restricted radiator, you could disconnect both the upper and lower hoses and run a garden hose into the upper radiator neck. Unless you have some sort of super water flow out of your garden hose, the radiator should be able to flow the water through without backing up out of the upper neck.

I am planning to do this, but can you give me an idea how big a water flow should be? I have no idea how the proper water flow volume should look like, I just read that the pros use a special tools to measure it.

Thanks again everyone for your support.

[chrism]

"...When it gets warm I can hear a very faint hissing from the cap..."

I'm not sure if that's OK. I've always assumed that the cap shouldn't pass gas unless the pressure becomes "unusually" high. I wouldn't think that if the temp gauge is at mid point or even slightly above, that the cap should be seeping. Here again, if compression is leaking into the water jacket after the engine warms up...... It would be interesting to see a compression test with both cold and warm engine temp. I suppose it's possible that the head is warping when warm. There are tests that can be performed that would detect combustion gasses present in the coolant.


"... can you give me an idea how big a water flow should be? ...

Gosh, you would have to ask that! I'm talking about detecting a MAJOR radiator restriction, where it's really obvious that it's not flowing well.

[Riba]

"...When it gets warm I can hear a very faint hissing from the cap..."

I'm not sure if that's OK. I've always assumed that the cap shouldn't pass gas unless the pressure becomes "unusually" high. I wouldn't think that if the temp gauge is at mid point or even slightly above, that the cap should be seeping. Here again, if compression is leaking into the water jacket after the engine warms up...... It would be interesting to see a compression test with both cold and warm engine temp. I suppose it's possible that the head is warping when warm. There are tests that can be performed that would detect combustion gasses present in the coolant.

I know, but they are not available in Kuwait. Many things are not, which is also a pain. However I do have my compression tester, next weekend I am going to test the compression and take a look at the spark plugs once I am there.

"... can you give me an idea how big a water flow should be? ...

Gosh, you would have to ask that! I'm talking about detecting a MAJOR radiator restriction, where it's really obvious that it's not flowing well.

Apologies for the stupid question, I suspected there was no advanced witchery to it.

[majorcode]

Riba,

Don't forget to post test results

[chrism]

"...Apologies for the stupid question, I suspected there was no advanced witchery to it..."

Not a stupid question at all. Seriously, when I wrote that I thought to myself "What if they ask what the proper flow volume should be?" I guess it's just one of those things where you say to yourself "That looks clogged" or "That looks to be flowing OK." If you do the garden hose test, just don't seal tightly between the hose and the radiator neck - the hose likely produces pressure that exceeds the limits of the radiator, especially if it's 15 years old.

Are there many Volvos in your area? Where do you normally get parts?

[Riba]

"...Apologies for the stupid question, I suspected there was no advanced witchery to it..."

Not a stupid question at all. Seriously, when I wrote that I thought to myself "What if they ask what the proper flow volume should be?" I guess it's just one of those things where you say to yourself "That looks clogged" or "That looks to be flowing OK." If you do the garden hose test, just don't seal tightly between the hose and the radiator neck - the hose likely produces pressure that exceeds the limits of the radiator, especially if it's 15 years old.

I hope I should be able to tell if the flow seems restricted, as I have never seen how a proper one looks like. I should be able to see if it is too low though.

Are there many Volvos in your area? Where do you normally get parts?

There are quite a few really, but this is definitely not the place to own one. You an get the parts only at the official dealer where the prices are 3x higher than what you would expect to pay, and there is another shop with limited stock and more sensible prices...and some aftermarket parts.
I was hauling bags of parts when I was returning from Europe, my wife wasn't too happy.

[Riba]

Getting ready to replace the damn temperature sensor, but no matter how deep I dig I can't get the info about the size of the three torx bolts that I have to remove. Can anyone confirm the size as I am planning to get a new torx ratchet head to minimise the risk of stripping them. The sensor itself is 19 mm, correct?

[precopster]

If they're shared with V70s and S70s they will be a T40 however I don't have first hand knowledge on S80s.

This is assuming the bolt size is M8

[Riba]

Thanks, they probably are. I just realized I got a set of torx keys which I can use to figure out the correct size.