Aitchy Posted April 27, 2019 Share Posted April 27, 2019 Hi All, Just joined and am looking for some help! I own a standard 2004 Impreza GX , had her for 9 yrs now and love her to bits! She has 117k on the clock. I`m having a problem, and am looking for some advice if I may! Started out of the blue, increase in engine temp when doing 70mph + on the motorway, not in the red, but not far off! Turned the heaters on full and she cooled back down. Other day the temp shot up within mins to just over halfway just travelling up to 30 mph in town on a short 6 mile journey to work. Parked at work for around 1.5 hrs put key in, didnt turn on ignition and temp went straight to first mark. Didnt do this again after and ran at normal temp round town ( I am a community NHS worker, so out and about all day stop starting). Had temp gauge changed, still same prob on motorway, fine round town. Not using any water, no leaks visable, oils fine. Rad cap checked, no gunge so next steps........check for blockage in rad, if not that could the water pump be failing and isnt able to pump enough water round to cool the engine at speed?! Anyone had any experience with this or have any thoughts please? Mechanic is certain headgasket is fine. Many thanks in advance! Quote Link to comment Share on other sites More sharing options...
Newman2213 Posted April 27, 2019 Share Posted April 27, 2019 I'm not a mechanic! If you can you use thermal imaging, or take temperature readings around the block, and system to check for hot spots before a coolant flush and swap Its cheap, easy enough to do and you could get a good idea of the contamination levels in the system. Are the fans kicking in correctly, is the the sensor that controls them operating at the right temps. Quote Link to comment Share on other sites More sharing options...
Greenmamba Posted April 27, 2019 Share Posted April 27, 2019 Any bubbles in the overflow when the engine is running? Has the thermostat ever been changed? How is the mechanic so certain it's not head gasket? Has the check engine light ever come on? Quote Link to comment Share on other sites More sharing options...
Aitchy Posted April 27, 2019 Author Share Posted April 27, 2019 check engine light has never come on , no bubbles! Fans are kicking in. Just changed the stat and still the same issue! Quote Link to comment Share on other sites More sharing options...
Brack Posted April 27, 2019 Share Posted April 27, 2019 Sounds like a radiator problem to me ...not a quick enough flow through - so noticeable temp increase at motorway speed . On one of my threads I was told that original Subaru water pumps are very well built and last 150K miles plus.... so I'd check the radiator next 1 Quote Link to comment Share on other sites More sharing options...
Greenmamba Posted April 28, 2019 Share Posted April 28, 2019 10 hours ago, Aitchy said: check engine light has never come on , no bubbles! Fans are kicking in. Just changed the stat and still the same issue! Was the stat changed in response to this problem? Was an original Subaru stat used or one claimed to be compatible? Again, what is the mechanic's basis for not suspecting HG? Quote Link to comment Share on other sites More sharing options...
Aitchy Posted April 28, 2019 Author Share Posted April 28, 2019 Hi All, thanks for your replies 😊 Ok, re-done all checks today! Oil is fine, no leaks, no bubbles, rad hoses fine, fans coming on when they should. Cant find anything untoward! I`m assuming the mechanic is going off the fact that all the markers are clear? Stat was changed in response to this issue and no not subaru. Going to check rad next, if thats fine then we move on to the water pump, on the sumise that it is not functioning correctly and cannot cool the engine enough at speed. Maybe we should do a pressure check to make sure the gaskets are ok?? Other than this problem, she is running as normal, in the 9 yrs I`ve had her nothing other than wear and tear has occured , had a new clutch fitted a few months back as it started slipping and cam belt was done in 2015, will change it again if the water pump has to be done, as daft not to! She`s been serviced regularly and my other half has always regularly checked everything anyway! anything else we should try?! Really appreciate your input. Quote Link to comment Share on other sites More sharing options...
Greenmamba Posted April 28, 2019 Share Posted April 28, 2019 First off, should have used Subaru OEM stat. Whilst aftermarket look similar and fit, our cars really prefer the original. The wax capsule of Subaru stats is larger allowing better opening and coolant flow. Subaru HG failures are often hard to nail down. normally no mixing of oil and coolant and sniff test can be inconclusive. Pressure test ditto; the problem is it's only when the car gets hot do the symptoms (overheating etc) manifest and that's when you can't easily do a pressure test. Leak down test might produce something interesting. When it gets hot, is coolant pushed into the reservoir and all drawn back to the rad when it cools down? Quote Link to comment Share on other sites More sharing options...
Aitchy Posted April 28, 2019 Author Share Posted April 28, 2019 Greenmamba, the other half is saying no , the levels never change. The thermostat is working, if it proves problematic later we will change it for a subaru stat. There is a slight whining noise coming from the front of the engine, which is more suggestive of the water pump? Quote Link to comment Share on other sites More sharing options...
Greenmamba Posted April 28, 2019 Share Posted April 28, 2019 Very odd that coolant doesn't expand into the reservoir when hot. It should - that's what it's there for. Was the car burped sufficiently when the stat was changed? These can be a bugger to get all the air out. Whining could be many things; pump, pulleys, ps, alternator etc. Quote Link to comment Share on other sites More sharing options...
Guest Posted April 28, 2019 Share Posted April 28, 2019 i agree with mamba but the fault was before the stat replacement, defo a cheap thing to check is the system bleed tho! . As you described motorway driving it leads me to think either, water pump failure or clogged radiator (internally or externally) . Have you carried out a coolant flush/change at all? after 117K i would suggest that crystallisation and contaminants of your coolant may have caused a clog usually in the radiator or the heater matrix ( thinnest points of coolant movement ). head gasket failure would show contaminated or loss of coolant or rise in oil level. Cheers Scott Quote Link to comment Share on other sites More sharing options...
Aitchy Posted April 30, 2019 Author Share Posted April 30, 2019 Morning all! Problem found, and resolved! fault with the rad! water wasnt circulating properly, can`t tell you how relieved I am!! You blokes probs think I`m a soppy female ( hehe) but I am very attached to my scooby roo!!! 😉 Thanks for all your input and advice 😘 2 1 Quote Link to comment Share on other sites More sharing options...
Jay762 Posted May 6, 2019 Share Posted May 6, 2019 Great to hear it was resolved 😊 Quote Link to comment Share on other sites More sharing options...
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