velohead66

Just wondering where exactly in the engine (or cooling system) the temp gauge measures the temp, for a MY98 Classic ???

Did a track day on Sat, with air temp at 31ºC (Australia).
The temp gauge AT ALL TIMES never went above what it normally does, so there was no indication that something was not right.

However, the journey home the car was not smooth, and felt like stalling, with smoke coming from the exhaust. Dark, not sure of colour.
When I got home, and checked the coolant the next morning, there was none in the resevoir.

I guess I'm looking at an expensive bill.

Head gasket or more likely to be a piston ring ???

Any advice appreciated (except non-constructive).

velohead66

I was hoping to get some info on the above.
Anyone have any idea ?

Splitpin

The coolant temperature sensor(s) are in the distribution main that connects the two halves of the block beneath the inlet manifold. On earlier cars there are two - one connected to the ECU and the other feeding the gauge on the instrument pack.

On later cars (99MY onward I believe) there's a single sensor feeding both.

velohead66

Thanks for your reply mate, I'm very worried by the engine, and the forth coming haemerage of $.

So, provided that the radiator has a certain level of fluid within it, say 75%-95%, then there will still be circulation of coolant around the block and heads.
Is that right ?

Also, if the engine overheats somewhat (but not bigtime), what are the possible implications....
warped heads
blown head gaskets
damged piston rings
any others ?

Just need to get an understanding, as the guy who does WRX engine rebuilds (including my 2.0L to 2.2L) has not returned my call as yet.

Splitpin

Couldn't answer that affirmatively one way or the other - a lot would depend on the way in which the car was driven after the problem started, and as you say you did do a track day.

Any significant void in the pressurised part of the cooling system compromises its efficiency significantly, as the compressibility of the air makes it much easier for the fluid (be it water or proper coolant mix) to expand (i.e. boil), so you get a vicious circle where the less fluid the easier it is for it to vent out, and the less there is that's in there the hotter the engine gets and so the quicker it'll go.

Possible implications include warped head face, HGs, potentially warped block in a really serious case - although if you've lost the coolant in the first place it's an open question at the moment how it left in the first place. Might be that a head gasket was the original problem, or might be you've holed a rad or something - do you recall following someone who'd gone off on gravel or similar?

The only way to get a proper handle on it is to have your man take a peek, or strip it down. You might be lucky.

velohead66

I agree, and when I get a few $ together, it will be down there.


The car is driven thoughtfully, in that I avoid gravel roads etc, but the car is always driven lively, ie the turbo does work hard when engine warmed up.

On track days (with bonnet vents off), I notice a very small 'puff' comes from right hand bonnet vent down main straight when I change gear. I presummed oil, so minor oil top up after each 6 laps. I think (now) that this was not oil.

Car has FMIC which in my opinion has compromised the air flow through the radiator, but the car also has new radiator due to split top hose some time ago.

I now understand (from a non subaru source), that even if there is no fluid, then the temp gauge will register normal.

The more I hear, the less I like it !!!

deanos scooby

hi there i hade the same problem with my scooby and just today i wos on my way home and the temp gauge whent past half way mark for the first time after a couple ov days ago the puff ov smoke come through my vent i looked at my tank and it wos empty so filled it up it wos ok till today so i pulled up at the petrol station and opened my bonnet herd hissing so i looked closer thinking i burst a pipe but it wasnt it wos comeing out ov my head gasket like a pressure washer so thats when i new it wos my head gasket lol but im lucky iv got some sti heads to put on cuz the temp gauge read norm i didnt now that the damage has bin dun so im goin to put a seprate temp gauge so it dont happen again why dont you try the same with a sep gauge are your hoses going hard as if there pressure in your hoses

Tazman861

iTrader: (2)

I have read on here that the standard water temp gauge is not very accurate. It may be better to fit a quality stepper gauge in addition to the standard gauge - that could show whether the standard gauge registered any changes.

SiofChester

iTrader: (2)

Check your radiator, they split on the right hand side which is only really apparent on boost. Cheap and easy fix