Overheating - again

Submitted: Tuesday, Dec 02, 2003 at 00:23
ThreadID: 8897 Views:1291 Replies:6 FollowUps:5
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Went down to Cornwall (700 mile round trip) last weekend: +/- 60 mph all the way with 3 x 20 mins stops. Took the caravan (1000kg) down and then came back without it.

Things went great, engine (4Runner 3.0 TD) hummed along and the temp. gauge stayed bang in the middle if the dial both ways. Problem is: every time I check my rad (every 100 miles or so), a sh*t load of coolant has been pushed out into the expansion tank. The rad isn't boiling hot too the touch and, as I said, the temp gauge doesn't move away from dead centre.

The weather was mild/cool and it rained most of the way back to Coventry is it my fan, fan clutch, belt slipping or what?

Anyone got any ideas as how to cure my cooling blues?
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Reply By: ronsdream - Tuesday, Dec 02, 2003 at 01:14

Tuesday, Dec 02, 2003 at 01:14
not sure what ur saying but sounds like ur motors temp gauge is saying its ok and ur rad is not boiling? right ? and the only thing thats worring u , is that the over flow tank is fulling with coolant (but not over flowing) ? if this is so then sounds like u got no prob? thats what the over flow tank is for, when the motor cools down the coolant should return back into the radiator., 60mph with a ton van on the backs a good speed , not up on the conversion but thats like 100klm/h or so right ?? if so try it at 80 or 90klm/h , much safer for you and every one else on the road, 4x4 + high center of gravity+towed weight 1ton+speed = accident waiting to happen
not baging u , just 22years of diving talking,but what do i know
cheers .and if i got it wrong about what u were saying was happening , then what i said probably dont help
AnswerID: 39132

Reply By: ross - Tuesday, Dec 02, 2003 at 01:17

Tuesday, Dec 02, 2003 at 01:17
Sounds normal ,thats what the expansion tank is for.When it cools the system contracts and sucks it all back in (actually atmospheric pressure pushes it back in ).
At freeway speeds the fan clutch will have turned off and the draught of air will keep the coolant at the right temperature .
Sometimes it takes a while for the system to find its own level of coolant and excess may overflow out of the expansion tank.
If your cooling system is ok the hoses should get pressure after 5-10 mins and hold it for some time after the engine is turned off.
If your radiator cap is removed while hot the pressure may not build up again until the cooling system has been through its contraction/expansion cycle.
If your still not satisfied with your cooling system I would recommend you fit a quality temp guage and monitor its movements and check with the manufactures specifications.
Long term overheating causes the oil in the cyl bore to heat up and thin out causing worn out rings/bearings ect
AnswerID: 39133

Reply By: ross - Tuesday, Dec 02, 2003 at 01:20

Tuesday, Dec 02, 2003 at 01:20
Ronsdream you beat me to the buzzer by a microsecond
AnswerID: 39134

Follow Up By: ronsdream - Tuesday, Dec 02, 2003 at 09:18

Tuesday, Dec 02, 2003 at 09:18
ya ya yar and to think i had only just joined:)
cheers ross
FollowupID: 82906

Reply By: Tony - Tuesday, Dec 02, 2003 at 07:04

Tuesday, Dec 02, 2003 at 07:04
G'day enzo, there are a couple of questions:

Is the expansion tank overflowing.

Does the radiator need topping up when it cools.

Do you get hot air from your car heater with engine running.

A problem could be blocked heater core, air in the system, or no problem at all.

I will be over in UK end of April next year, we should try and catch up.
AnswerID: 39136

Follow Up By: enzo- Tuesday, Dec 02, 2003 at 07:51

Tuesday, Dec 02, 2003 at 07:51
Hi Guys and thanks for your answers -

To reply to some of your questions: 60mph is the legal limit for towing a caravan on the motorway - basically everything passes you except for the odd three wheeled Robin Reliant! This is on good 6 lane metalled highway and not dirt track or anything and I do understand your warnings but we weren't endangering anyone.

Maybe I'm too impatient - when I stop I allow the engine to run for 3-5 minutes and then I check the overflow bottle. If it has pushed out alot of coolant I check the rad is not too hot and then ease the lid off. As long as only a bit of pressure escapes (not too much) I'll check levels. If the level's low, I siphon whats in the reservoir into a jug and put it back in the rad, so maybe I am not waiting long enough for the pressure to return the coolant back to the rad.

Tony, to answer your questions:

The expansion tank wasn't overflowing, I couldn't wait for the rad to cool properly and filled it up hot (with the old coolant the first time and then I had to top it up ther second time); I get hot air from the heater with the engine running and this rad is only 1 - 2 years old so there can't be any sludge build up.

I think I'll have to stop panicking and see how it goes next time when I leave it to recover naturally - it's just that I've been burnt (financially) by a "porous" cylinder head before and am wary of being burnt again.

As to coming over Tony: your welcome anytime, infact if anyone from the forum is in my neck of the woods, please pull in for a beer or two, and if you need somewhere to kip - just pull in, I can't promise you a braai but my wife does a pretty mean curry!

FollowupID: 82903

Reply By: ronsdream - Tuesday, Dec 02, 2003 at 09:35

Tuesday, Dec 02, 2003 at 09:35
OHH :) your in the UK sorry matey i thought you where in aussie land lol , well i got no idea what your roads are like over there , but 6 lanes sounds pretty cool lol, but as i said ,i wasnt backing u. or taking the bleep out of you:), and legal speed dont mean safe speed ,was just my 2c worth matey,
And a good simple check for a F@#ked head is to take the cap off you radiator start the motor up, and check for bubbles in the radiator and an oil film in it ,as well, and or water in your oil. (this will give you a milky color in your oil , helpfull hints in saving you money;) cheers matey and happy trails
AnswerID: 39157

Follow Up By: ronsdream - Tuesday, Dec 02, 2003 at 09:42

Tuesday, Dec 02, 2003 at 09:42
meant to add to that a good raod does make a differance
hope your motors cool
FollowupID: 82908

Follow Up By: enzo- Tuesday, Dec 02, 2003 at 11:01

Tuesday, Dec 02, 2003 at 11:01
No worries, but I do wish I had the bucks to fit a larger rad or even just to increase the capacity of the one I've got.

Stay well,

FollowupID: 82922

Reply By: Mick - Tuesday, Dec 02, 2003 at 20:49

Tuesday, Dec 02, 2003 at 20:49
Stop worrying enzo. Engines are intended to be hot. The thermostat usually keeps them at 180-190F so they are hot to touch!! If you're not losing coolant from the overflow bottle and the guage is staying normal don't worry. You'll soon know if your engine overheats!! They make loud hissing noises. DON'T remove the radiator cap unless it's cool!!!!! If you think you're losing too much water try replacing the cap - not expensive and if it doesn't change the amount of water going to the overflow it's always handy to have a spare. If the spring loaded washer isn't strong enough it may let too much coolant out.
I'd be a bit cautious about towing at that speed with a small 4wd. Cruiser or Patrol is fine but a 4 Runner is a bit on the small side for safety.
AnswerID: 39216

Follow Up By: enzo- Tuesday, Dec 02, 2003 at 21:13

Tuesday, Dec 02, 2003 at 21:13
Thanks Mick et al, and I'll take the advice re: towing on board and cut down on the weight of my tows. I don't think it was the weight so much (closer to 700kg than 1000) but the extra drag resisitence involved. Anyway, thanks for all the advice.

I'm off to Zimbabwe on Thursday and so I'll wish you all a very merry xmas and a happy new year now, as I won't be back until early Jan.

Stay well,

FollowupID: 238441

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