Coolant problem - wierd

[T5rookie]

Hi guys,

Got an issue with the 850 I just picked up, not worried as the work to fix it is going to be paid for by the previous owner as soon as I diagnose it.

Ok so I left northampton with the car on max line for coolant......I checked and checked again, no mayo in the oil, no oil in the coolant, no smoke on startup or when running/overrun. No overheating either.

Series of events.....

Took ages to get warm and up to halfway.
When it eventually did it would drop down to a third temp whilst on the motorway.
However on stopping or trafiic/lights, the temp would rise to half way again....Once fan kicks in it begins to drop again on the open road.
Coming up to services I noticed upon hard acceleration the low coolant light was flashing due to it reading below minimum when accelerating hard/nose lifting.

So I got 10 miles from home and popped the bonnet whilst I grabbed a kfc, just to check everything again.

This is when I noticed the coolant level was at minimum....So I slowly opened the filler cap to release any air if it had been getting blockages. Low and behold a massive amount of air released and the coolant level came back up to near the max line.

I noticed when home and engine cooling down that on sqyeezing the rad pipes, you could hear air stuck in there.

So after a long run I now have to release the filler cap and any air blocks to get the coolant to sit right again. If I just keep driving it the coolant level continues to drop???

I had to top the system up with 300ml to bring it to the max line.

There are no leaks anywhere at all, no split hoses, no overheating....Just a temp gauge that fluctuates between half and a third, and a lowering level in the filler tank.

My thoughts -

Sticking thermostat?

Would this cause the dropping of running temp as it is getting partially stuck open at times, and could this prolonged action be causing air locks? Finding their way to the filler tank, therefore pushing the coolant around the system and making it look like it has lost cooant in the filler tank?

Or

Wrong thermostat? Opening and closing at temps different to that of volvo specs....so causing fluctuating temps.

Or

Headgasket? But surely I would be seeing high temps/mayo/oil in coolant, boiling coolant....

Any ideas?!? I am mechanically minded and can do most things but if its more serious I will need a garage to do the work.

[mark850r]

My brother inlaw had the same problem but on another car when i had a look his thermastat was stuck open he had the same issues as you so i changed it and all has been ok since.
so this would be were i would try first.

cheers mark

[T5rookie]

cool.....ok will do the thermostat in the next few days.....is it best to do a coolant flush or can you get away with changing it without dropping the coolant

[Haizum74]

cool.....ok will do the thermostat in the next few days.....is it best to do a coolant flush or can you get away with changing it without dropping the coolant

You can change it without changing the coolant but why not kill two birds with one stone and give it some fresh stuff?

If there was air trapped in the lines or rad then I am led to believe you would see the dial go to max on the gauge.

Incidentally mine is doing similar to this but not using any coolant, am going to try a flush and change thermostat. Could also be temp sensor I think!

[Volvostorm]

What colour is the coolant bottle cap?

The grey coloured one loses pressure, which would allow the coolant to boil.

You want a green cap.

[T5frankie]

just done my stat as was opening about 60 degrees therefore not heating the waster up properly

[PHIL V70R]

air lock...i had 2 run mineon the drive till it came over the top of the coolent tank, then i let it cool down and refilled it..its ok now..

[T5rookie]

I have the green cap

Will keep the thread updated after I have swapped the thermostat and flushed the coolant! Where are the bleed nipples for the rad? Or can you just vent the air through the cap?

[Volvostorm]

Doesn't have any bleeds, its just a cap off job.

[Kingsford G]

I`d not be surprised if yr head gasket on its way out and to flog it the owner removed the stat or the valve in the stat.All above simptoms do indicate on that.However I hope not but u need to remove the stat first and if in one piece replace it.Also loss of coolant can appear as a needle little hole leetting it out as a steam.Anyway,stat first.If no stat or no valve in the stat I`d take it back.

[T5rookie]

As I have stated mate, the previous owner is paying for the work as he was genuine and feels crappy that there was a problem. I don't need to take it back, just let him pay for it whether it be thermostat or head gasket.

He owed it for 15 years and was almost retired with 3 volvos so I doubt he was trying to just shift it on as a dodgy bloke. The amoutn he spent on it especially.

[T5rookie]

I`d not be surprised if yr head gasket on its way out and to flog it the owner removed the stat or the valve in the stat.All above simptoms do indicate on that.However I hope not but u need to remove the stat first and if in one piece replace it.Also loss of coolant can appear as a needle little hole leetting it out as a steam.Anyway,stat first.If no stat or no valve in the stat I`d take it back.

Its a pretty rare thing for a bone stock 90k t5 engine to crap a head gasket isn't it? Especially with full service history. He's no mechanic either, all main dealer so he would have had to pay a main dealer to remove the guts of the stat.....not likely.

Gonna try and get a sniff test done tomorrow to be sure.

[Kingsford G]

As I have stated mate, the previous owner is paying for the work as he was genuine and feels crappy that there was a problem. I don't need to take it back, just let him pay for it whether it be thermostat or head gasket.

He owed it for 15 years and was almost retired with 3 volvos so I doubt he was trying to just shift it on as a dodgy bloke. The amoutn he spent on it especially.

Well I didn`t know the background of it so I don`t suppose he flogged it full off rubbish then.Check the stat is a N 1 job.

[T5rookie]

Pretty sure its the thermostat.....Will pick one up tomorrow....

Reason being it was much colder today and on an 8 mile trip to the gym it barely got past 1/4 heat! Must be jammed half open so its constantly pressurised and the coolant isn't finding its way back into the top up tank properly.

Which thermostat do I need as eurocarparts stock 3 or 4?? Different opening temps?

Alex

[Kingsford G]

Pretty sure its the thermostat.....Will pick one up tomorrow....

Reason being it was much colder today and on an 8 mile trip to the gym it barely got past 1/4 heat! Must be jammed half open so its constantly pressurised and the coolant isn't finding its way back into the top up tank properly.

Which thermostat do I need as eurocarparts stock 3 or 4?? Different opening temps?

Alex

Did u say yr pipes pressurising?

[T5rookie]

no....there is air in the system somewhere and it needs a release of the coolant filler cap to get rid of some of some of the air.

Rad pipes stay firm but easily squashable.....

I can't see a well cared for 90k block with fsh pooing its head gasket unless it was a faulty item to begin with?? WOuld be the first case of head gasket I have seen which doesn't show smoke or any oerheating.

Another member has just had the same issue of coolant level dropping, some air releasing from coolant cap with no overheating and no exhaust smoke and was his thermostat.

If it had blown between the water journal and piston chamber the coolant would smell of exhaust gas and slowly go grey wouldn't it? Other way being oil in the coolant or a drop in compression.

Either way on a very low mileage lump I would be amazed if your theory of a head gasket is the result

[T5rookie]

just been out to check coolant level....

Seemed ok but noticed dried coolant drips/spatter on the filler tank around the cap??!

[merc85]

just been out to check coolant level....

Seemed ok but noticed dried coolant drips/spatter on the filler tank around the cap??!

Partially blocked rad would do this, ask Bigrotch

[smithson007]

You can get a volvo stat for around 20 quid i think. Did mine just the other week. I also did coolant temp sensor at same time. I think its a 90 deg stat you need.

[T5rookie]

So volvo stat is over twice the price of any motor factors? Is there any benefit?

So to recap I could have:

Head gasket failure
Blocked radiator
Knackered coolant cap
Knackered thermostat
Leaking heater matrix

This is going to be expensive to diagnose isn't it? It's my only car so can't afford to have it off the road for long, and I can't just open my wallet and replace all the above as its gonna be a big bill! All this on top of suspected rear main seal........ffs!!