Took a drive in the afternoon and noticed that the car's water temp was running about 10* warmer than usual (180* t-stat, 195* fans on ... ron davis radiator w/ dual 16'' fans). Oil temps were normal.
Usually when I'm driving and it's warm, water temps are around 180*, now they were 190*. idling in traffic when the fans come on at 195*, temps usually drop, but today they rose to about 205*, then slowly came down, with the fans staying on much longer than normal. For example, I think i had to drive for about 5minutes before the fans turned off (off at 175*).
I then took a test drive in the evening (much cooler air temperatures) and was expecting the water temps to be around 170* when moving at speed, but they were closer to 185.
3,500miles and no problems (last time i drove it 2 weeks ago it was fine) so I'm thinking maybe it's the thermostat and it's either partially stuck or opening later? Anything else i should be considering?
I did note that the upper radiator hose is hot (much hotter than the lower radiator hose, but it may not be a fair comparison because the upper hose is rubber, the lower hose is the corrugated metal variety). Also, if the car is idling at, for example, 190* (above where the t-stat should be opening), i can grab the upper hose and squeeze it completely together (like I was trying to block the flow of coolant manually) .... is this normal? I would have thought, with coolant flowing through it, it would feel solid or slightly hard, not empty with me being able to squeeze it together to stop flow?
Agree your thermostat sounds suspect based on what you describe and what has changed. That's an easy (and cheap) first place to start.
For the record, the temps you describe aren't too hot. You don't say what engine you have, but a SBF is very happy at 190-200. If fuel injected, should have a 192 thermostat to work properly. A lot of guys run a 180 in a carb version, but 192 works fine with a carb as well.
I agree - my water temps arn't dangerously high - however it concerns me when I drive the car for 3 1/2yrs and water temps always behave the same, the one day they decide to become 10* higher.
Just like today is the first day ever, when idling, my water temps came close to 210*, and there was nothing special about today (e.g., warmer than usual)
Better to nip stuff in the bud when you notice it than one day be driving and go 'hey, how come my temps are 210...220...230....! :/ '
Btw, for reference, what should the upper hose feel like with a fully functional t-stat? Should I be able to 'pinch' the hose together with 2 fingers? (I imagine not since coolant should be flowing through it, so it should offer some resistance?)
If you can squeeze the upper hose when the engine is fully warmed, you have no pressure in the system. Likely your cap has failed, and you have lost water.
If you can squeeze the upper hose when the engine is fully warmed, you have no pressure in the system. Likely your cap has failed, and you have lost water.
The best way I can describe it:
Water temps are above the t-stat opening point (e.g., temp of 195*, t-stat opening 180*)
The UPPER radiator hose (rubber) is bloody hot, I can only hold it for 3-4 seconds. THe lower radiator hose (corrugated stainless material) is warm and holdable until the end of time. I know upper/lower should be similar temps, but I don't know if the corrugated stainless is shedding heat faster, thus the temp difference
With the engine running and at the above temp, i can (briefly...very hot!) grab the rubber hose and pinch it shut with 2 fingers. If i keep holding it, I don't feel any pressure or anything. if it weren't so hot I could probably hold it forever pinched shut
I didn't it was because coolant levels in my remote resevoir look about normal, but i have a spare one so it's a quick thing to check
But what should a normal upper rubber hose feel like if t-stat and everything is functioninig properly and the engine is at temps? Should it feel heavy from water inside of it? should it be scalding hot or just hot? should it be rock solid or solid with a little bit of give? I ask because when I research I find some people who say the hose being harder at operating temps than when cold is normal, others who say 'any hose hardness = head gasket failure!!!11!!!', so i dunno.
Last edited by BingBangBob; 09-09-2012 at 05:09 PM..
The upper hose normally would still be squeezable, when as hot as you describe. (An older hose is often not as stiff as a new one). Water pump pressures are not so great that the hose would be really firm.
The lower hose should be somewhat cooler, as the coolant has passed through the rad and presumably, has cooled down some. Although it's normally pretty hot even still, to the touch, stainless or otherwise.
If your coolant is not passing through the rad at a normal rate, due to blockage by say, corrosion, you could be seeing higher temps than normal, and a cooler than normal, lower hose. That or there is not enough coolant volumne passing through the T stat.
The easiest thing to do initially, would be to change out your T stat for a new one, and see what happens.
I replaced my rad cap and at 170* the hose was soft (could squeeze together with 2 fingers), 180* it starts to warm up and at 190(ish) it's warm and the hose is squeezeable, but there's no way to squeeze it completely together with 2 fingers
Temps back to normal, although I did note something weird - when driving water temps are a solid 183* degrees. Obviously this isn't a concerning temperature, I just find it weird that previously it was always a solid 180*, although that was with a failing cap so who knows. i guess just monitor
With 15-16# pressure developed in the cooling system, you should not be able to pinch the hose closed. Could you pinch a bicycle tire closed if it had 15# pressure? Since the old cap wasn't holding pressure, it should have pushed more water into your overflow tank than it normally would. Keep an eye on your water levels. You may have lost some water you haven't noticed.
With 15-16# pressure developed in the cooling system, you should not be able to pinch the hose closed. Could you pinch a bicycle tire closed if it had 15# pressure? Since the old cap wasn't holding pressure, it should have pushed more water into your overflow tank than it normally would. Keep an eye on your water levels. You may have lost some water you haven't noticed.
After replacing the cap i can no longer pinch it closed - it feels normal, thanks for the suggestion - I wouldn't have thought rad cap :O
I burped the system and water levels seem normal, but will still keep an eye on it.
Last question for today if somebody could help me out.
It's fairly warm outside, so I took a hard cruise. oil temps were nice and toasty - 210 to 220 (toasty for a street drive that is, heh) - my water temps were a solid 182-183* unmoving depending on if i was just coasting in 5th, or throttling it in 3rd. Rock solid.
So what I'm wondering is, given I have a 180* t-stat, is it acceptable for the water temps to be a few degrees above it? i'm less concerned than when i was seeing temps of 195 while driving yesterday, but still not certain if I should be seeing temps pegged at 180* because of a 180* t-stat.
In terms of idling it idled strong at 195* when the fans kicked on, then cooled down to 175-180 within 30-40seconds of the fans going, so that was good.
Last question for today if somebody could help me out.
So what I'm wondering is, given I have a 180* t-stat, is it acceptable for the water temps to be a few degrees above it?
Unless I am really pushing the car, my coolant temps remain just slightly above the T stat rating..you should be good to go.
Great that you got it sorted out, and it was only a faulty cap..
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