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Overheating when stationary or under load.

Ben Up North

can only hope to improve
Joined
Oct 1, 2017
Messages
2,115
Location
FNQ
Car Year
2004 | 1992
Car Model
SG Forester X MY05 | 92 SVX
Transmission
5MT D/R | 4EAT
I've got a 2004 SG Forester, after the engine has warmed up, it gets massively hotter (noticeably above second line on temp guage) when stationary or climbing steeper grades - higher revs seems to cool things down (i.e changing back a gear when climbing). Cruising on the flats it's as cool as a cucumber.

Any suggestions? fans are kicking in, could it be a water pump issue or a blockage/flow restriction somewhere?

:confused:

Any helps would be goods,
Ben
 
Hmmm.. maybe it's a coolant issue. The stuff in there is green, and everyone here seems to be talking about blue stuff.
 
Further to this.. increasing the revs when stationary rapidly lowers the temperature guage.

Which seems to imply to me that it's a flow through the motor thing.
 
I would suspect the water pump. Green coolant is fine.
 
^ Ah yes I agree, of course, the thermostat completely slipped my mind!
 
Also check your heater circuit. If there's a blockage this can cause issues with the heating of the thermostat and thus it's opening.

That or you've lost coolant somewhere and have low coolant level... Long shot?

Cheers

Bennie
 
revs when stationary suggests (as above) a partial blockage maybe.

Check for kinks in the lower hoses, pull the thermostat out and check it.
 
Thanks everyone for all the suggestions.
I'm going to take a guess that they didn't burp it when they checked for leaks, because I just added a heap of coolant and it's made a hell of a difference. The resevour was full though, so not sure what's going on there, or even if that would be expected, seeing as the radiator was so low..?
 
That could be an indication of a thermostat issues if the reservoir is full. If the thermostat doesn't open you get boiling and back flow.
Keep an eye on the temp gauge.
 
Thanks everyone for all the suggestions.
I'm going to take a guess that they didn't burp it when they checked for leaks, because I just added a heap of coolant and it's made a hell of a difference. The resevour was full though, so not sure what's going on there, or even if that would be expected, seeing as the radiator was so low..?

Ben, check that the radiator overflow pipe is tight on the fittings at both ends. It might be blowing coolant into the reservoir when hot but hasn't got enough vacuum to suck it back as it cools. Happened to mine once.
 
Also have the radiator cap pressure tested or just get a new one.
 
Thanks for the suggestions Kevin.
Took it back to mechanic and they pressure tested it again - assured me they had done the coolant correct first time, so could possibly be that overflow line. Will check.
Radiator cap sealer thingy seems to move ok, not stiff anyway.
 
The continuing saga..

Currently car temp appears to be fine when cruising or stationary, cool as a cucumber.
Whenever I do long climbs (which is just about every time I go out, there's always a 15-25 minute steady climb up the range, regardless of which way I go) the temperature slowly increases until just above the second mark. As soon as I level out the temperature reasonably quickly drops to normal.

No issues whatsoever so far off-road, although I haven't' done any really long ascents, only short ones.

Don't seem to be losing coolant.

I haven't replaced anything since last issues. Have added the Blitz 240s onto the front, but I really don't think they're the issue as the car was doing this before I put them on.

So currently I'm thinking:

Maybe the thermostat isn't opening far enough, restricting flow when it's really needed..? Does this sort of thing happen with thermostats, or are they really just opem or closed?

Perhaps the water pump is dying, and thus not able to push the water around enough?
Or even there's a heap of gunk in the engine from thousands of K's being driven at relatively low revs (used to be predominantly the wifes daily driver and she's not big on the accelerator) and was used for a lot of short runs (5k's or so) with the occasional (4-5 times a year) longer runs for camping etc?

I don't think the thermostat or water pump have ever been replaced.. if replacing them, as I'll be paying someone else to do it would it be cheaper doing both at once?

Mechanic hasn't mentioned anything about water pump or thermostat possibly being dodgy and he's aware of the issue.

Maybe it's just my driving style..? Should I be increasing changing down and increasing revs earlier when climbing? I generally like to be about 3000-3500 when climbing, changing down and revving harder doesn't seem to improve things temperature wise..
 
Thermostat could be faulty, radiator and/or condenser could be full of mud or dirt. Radiator could be blocked. Or maybe head gasket or cracked head.
 
Thermostat could be faulty, radiator and/or condenser could be full of mud or dirt. Radiator could be blocked. Or maybe head gasket or cracked head.

Radiator just recently pressure tested and checked - not that old either, certainly not full of mud. Condenser clean too.

re Head Gasket - drips a little oil, not enough to require top up between servicing. Oil itself doesn't appear milky or cloudy.

Doesn't use coolant (but it seems mechanic doesn't burp it properly because I always invariably need to top it up once after they've done anything to the radiator)

Cracked head - what other symptoms would/could it show?

Can a thermostat be faulty and not open as much as it should? Or if it's faulty would it just not open at all (Or conversly, remain stuck open)?

we generally just use bog standard ULP, could changing fuels be any benefit, being that it's n/a?

Is it possible that the engine is just gunky after years of relatively slow revs (it never gets pushed that far) - is there anything that can clean an engine? I've always been sceptical of additives..
 
You say it doesn't use coolant but needs topping up. How long after work has been done on the radiator does this go on for? Otherwise change thermostat.. Fuel would be irrelevant. Revs irrelevant too. Lack of servicing though can cause problems. How many k's has the water pump done?
 
You say it doesn't use coolant but needs topping up. How long after work has been done on the radiator does this go on for?
Only ever need to top it up once, usually after about an hour of driving or so, then it's good until the next time they fiddle with the radiator.

Otherwise change thermostat..
Judging by the feedback, that's the next step. I should probably have had it done last service. Might attempt it myself..

Fuel would be irrelevant. Revs irrelevant too. Lack of servicing though can cause problems. How many k's has the water pump done?

thanks re fuel and revs, didn't think it would make a difference.

But.. the car has occasionally gone over its service, up to 1000ks.. :(
It's been serviced at correct intervals for the last couple of years (since it stopped being a daily driver)
Not sure if the water pump's ever been changed - car has now done just over 166,000. It certainly hasn't been changed in recent years from memory. I should really see if the mechanic can get out a history of what we've done.

Would changing the water pump and thermostat at the same time reduce cost if having it done by a mechanic, or irrelevant in terms of labour?
 
Ben, the water pump is at the bottom centre of the front of the block. You have to pull the front of the motor apart to get at it.

Good idea to do the timing belt at the same time.
 
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