A few months ago I had a big overheating episode, top blew of expansion tank and steam everywhere. Garage found rad cap seal had gone so fitted aftermarket cap, (however I recently checked the pressure rating and it is slightly different to the genuine Toyota one).They also pressure tested system and it ran fine until just before Christmas. Now I can get about 30 Miles with the temp gauge (temp alarm fitted to remove "dead spot") hovering around normal then suddenly the gauge jumps to red mark. If I then pull over the expansion tank is full with evidence of lost coolant from the overflow, and If I leave engine to cool down over about an hour the coolant gets sucked back till the tank is upto the full mark (If I leave it longer it eventually empties the expansion tank). However If I then remove rad cap, the coolant level is low and needs about a litre to top up. Then I can go about another 30 miles before it happens again. No evidence of cylinder head problems (Yet) or major coolant leaks (I suspect there may be a tiny leak somewhere though), oil is clean etc. I will replace the rad cap with a proper Toyota one, but I suspect that isn't the only problem as It's been going fine for several months with the wrong cap. So any ideas for likely culprit? These have been suggested :-
1)Rad Cap
2)Thermostat
3)Airlock (How do you clear them on the Townie?)
OR Combination of the above! or something else?
I need to get this sorted ASAP.
Cheers.
Martin.
- (#7517) Martin King, 5 Jan 04 15:31
How much different is “Slightly different”?
To much pressure will cause the cooling system to start leaking at the joints, to little pressure will allow the coolant to boil.
Try a new Toyota float type radiator cap, part number 16401-64501. If you can’t find one locally then try dave Coombes on the IOW. He supplies mail order.
- (#7517) dave Bright (Bournemouth), 5 Jan 04 15:51
If it's blowing out it's coolant within 30 miles, I hate to say it but it sounds like the HG. All you can do is fit a new OEM rad cap, ensure that there's no airlocks, and hope for the best. I'll bet it still does it. Or you can arrange to have a pressure test done on the engine- connect a gauge to the cooling system (sometimes stuffing it into the overflow hosse works)and start her up. There should be NO pressure for the first few minutes until the coolant starts to heat. If it pumps the system up within 30secs, you've got HG problems...
Methinks your previous overheating event has cooked'er
- (#7517) david miller, 5 Jan 04 16:10
Hello Martin,
Viscous coupling..........
After my engine re-build a few years ago I suffered with one of many over heats on the way home, a journey of 50 miles. When I pulled over and looked closer at the problem, my expansion tank was pressured and pushing coolant out through the overflow. Once cooled, the system took about 2 litres in the rad cap and further fluid in the expansion tank to bring it up to the correct level.
I still took the vehicle to and fro work, a journey of 27 miles where if I kept the revs below 3000, about 50 mph ( A roads ), I never lost any coolant. If I went the Motorway way home, 35 miles at 70mph I needed about a litre of coolant for each trip.
I went through 3 rad caps and the garage took it back twice to pressure test the system and check for exhaust gases in the coolant.
I then had an offer from a contributor to the BoK of a viscous coupling he had in his shed, I gave it to the garage to fit and never had any further problems. I did have some suggestions from helpful people here on how to test the original one whilst it was fitted but when I did them I didn't find them conclusive one way or the other.
I hope this may be of help and for further information you can also check the archives at ace answers.
- (#7517) Mark, 5 Jan 04 16:32
Re. Dave Bright's post
>How much different is “Slightly different”?
The rad cap is marked 108kPa which converts to 1.08 bar or 15.7psi rather than the Toyota 0.9Bar or 13psi
Re. Davis Millers Post
There are NO other signs of HG problems, coolant is normal colour and oil is normal, also if the system was pressurising that quickly would it not fill the expansion tank almost immediatly? Also starting the engine with the rad cap off AIUI should expel coolant out the filler, but this isn't happening. It could be wishfull thinking on my part but I hope you're wrong :-)
- (#7517) Martin King, 5 Jan 04 16:34
Mark, Your problem does sound VERY close to mine,and thinking about it I haven't noticed the "fan roar" recently, if it is the viscous coupling, any suggestions for a "quick and dirty" fix until I get time to get it off the road and looked at? If I lock the coupling what are the long term effects of over cooling are they as bad as over heating?
Martin.
- (#7517) Martin King, 5 Jan 04 16:40
Martin, if it is the viscous coupling, I nursed mine through by keeping the revs down, not an easy thing if you do motorway travelling. One of the problems this time of year with locking the coupling is the possibility of no heat for you or the windscreen and a higher fuel consumption.
The others may be able to help with the more technical possibilities of cold engine running.
- (#7517) Mark, 5 Jan 04 16:57
No, good answers Martin. We're very used to a particular set of symptoms round here, and the autopilot tends to be worst case...
Search the archives for the thread test for the VC, and don't attempt to lock it. It's not meant to spin at full speed.
But check carefully for a SMALL leak in the system. Try to get it pressurised COLD (bicycle pump up the overflow...)and look for wetness. All you're looking for is enough to lose a pint or two over that 30 miles. Normally it'd steam off, that's why a cold test is good. Rad end tanks are favorite, plus thermostat "O"rings...
As you lose water, you lose pressure also, until a time comes when there's insufficient water to keep itself from boiling internally. Next stop blowout and overheat!
- (#7517) david miller, 5 Jan 04 17:22
Re. the thread test for the fan I may try something more scientific, I have access to a calibrated strobe at work so I should be able to accuratly measure the fan RPM, dunno how long it will take to get upto temp when static in this weather though?
Martin.
- (#7517) Martin King, 5 Jan 04 17:46
If your Rad cap is rated higher than the recommended 0.9 bar surely it's a strong possibility that you've a leak at some hose, because the system is being over-pressurised before the Rad cap opens ?
Not all the hose retaining clamps are the worm type fitting !
I found a poorly fitted clip type fiting, on the return to filler pipe - from Rad, was responsible for some water loss I had last year and that was with a deteoriating seal on the correct Rad cap.
Under normal town driving it never used water.
It was only when fully loaded and after a motorway drive that I found steam escaping.
- (#7517) stephen judge, 5 Jan 04 18:16
BTW Forgot to mention in my previous posts I am going to replace the rad cap regardless, (ordered one from local Toyota dealer just before New year and it apparently came in Today, I'll probably also replace the thermostat when I get time, just in case.
Martin
- (#7517) Martin King, 5 Jan 04 20:56
1.08 bar or 15.7psi is a little high, so it would be advisable to check the hoses for swelling, or damage. To check the seal on the ends of the hoses, try to turn the hose near the clip that secures it. If the hose can turn on the fitting, then it wont form a good enough seal to prevent loss of pressure. If you find any that turn, then a temporary fix is to move the clip to a new part of the hose. Then get a replacement hose asap.
Hope you have some good luck with this.
Regards
dave Bright
- (#7517) dave Bright, 6 Jan 04 04:18
If the system is in good condition, the extra pressure can do no harm. The extra couple of psi <might> stress a marginal hose, but that additional pressure will give you maybe 5 degrees more before the coolant will boil. Peugeot/ Citroen diesels have had this higher pressure cap for many years...
- (#7517) david miller, 6 Jan 04 11:08
Bugger it! went to the stores today and the strobe has been disposed off because "no one ever used it" And Local machine mart didn't have an optical tacho in stock, So a quick and dirty fan speed measuring setup has been devised with stuff that was laying around :-), two small magnets on opposite blades SECURELY taped on, Pickup coil (actually one of of those things you use to record phone calls) mounted on a stick again SECURELY so it's about 1" from magnets. Coil fed to frequency counter, multiply frequency on counter by 30 to give RPM. Tested in the workshop using a pillar drill at 2500 rpm, works fine, so I just need to set it up on the car tonight. It can even be used when mobile for a short while (risk of magnets flying off eventually, if gaffer tape loses its grip!) as long as a passenger monitors the fan speed ! I wonder if it's worth devising a permanent setup with a display in the cab along with a display of air and coolant temp and system pressure (or is that a little overkill and I'm getting too paranoid ;-)?
Martin.
- (#7517) Martin King, 6 Jan 04 12:11
Not paranoid, but try to get to the bottom of your problem first...
- (#7517) david miller, 7 Jan 04 02:40
OK latest is :-
Drained system, old coolant was clean.
Replaced thermostat. (checked old one anyway against new one and it was OK)
Replaced rad cap.
Refilled system
Checked VC fan, OK
(BTW method used to test VC when van is static was to run it for a while at around 2000 rpm til engine was nice and hot but WITH THE HEATING COMPLETELY ON, I.E. slider to max hot and fan on full. Then quickly kill both the heater and fan, this seems to cause a rush of extra heat through the system, which on my vehicle activated the VC fan almost instantly)
Took it for a test drive today, mixture of rural and motorway, didn't go above 70, got to about 30 Km (18M) and the gauge started reading worryingly hot, pulled over and the expansion was full with evidence of coolant expelled from the overflow, left it my standard hour but the expansion had only dropped about a third of it volume rather than back to the full line as before. Removed rad cap and topped up with about 1/4 litre so not a huge amount. Took the same journey home but this time kept to 2000rpm all the way (speed between 30/40mph) (luckily not much traffic around :-) The temp gauge kept trying to creep up but I just kept backing off till it dropped again. Got home and expansion tank level hadn't changed! left it an hour again, took rad cap off and the coolant had only dropped about 1" below the normal level, I would have expected a leak in the system bad enough to cause this sort of overheating to have lost more than that over 30Km even with the revs kept low, the system pressure would have still been reasonably high I'd have thought?.
I'm mystified! Any more ideas?
Martin.
- (#7517) Martin King, 8 Jan 04 18:20
Check the small coolant pipe that takes the coolant from the back of the head thro the cold start device on the fuel pump to the the lower block for a possible blockage.
This can be checked by feeling the hose to check its temperature.
Phil.
- (#7517) phil, 8 Jan 04 19:03
This is beginning to sound like a blocked radiator. I'm not sure if your van is 2wd or 4wd, but if it's a 4wd auto, then you have two radiators. One vertical in front of the engine, and the other is horizontal under the front floor, mounted below the air-conditioning radiators.
One of these could be blocked, so a descale and flush might help.
Regards
dave Bright
- (#7517) dave Bright (Bournemouth), 9 Jan 04 03:12
Dave, It's a 2wd auto, no horizontal rad. I can only find one drain point, a tap on the drivers side at the bottom of the radiator do you know if there are any more? The bore of the drain tap seems a bit small so I'm worried that any flushed gunge may not find it's way out fully, I suppose the other option it to remove the large bottom hose the other side of the rad.
BTW I hope this thread is being educational :-) Sorry it's dragging on a bit.
Martin.
- (#7517) Martin King, 9 Jan 04 05:52
Hi Martin, there is a drain on the engine block, but the advice on the archives is to leave well alone. If you loosen the radiator tap, it will unscrew and fall out, which gives a bigger bore. Only one cautionary note is that there is a small O-ring on the end of it that gets flattened, so a spare would be handy. Sorry I can't remember the size.
If you remove the top and bottom hose, then shove a hose pipe in the top, it will give an indication of how blocked the radiator is.
- (#7517) dave Bright (Bournemouth), 9 Jan 04 06:03
Just stepping back a little (haven't read the posts for a while) Mine recently had a small rad leak at the top. For weeks I couldn't find any evidence of it but need to top up about a pint every few of days. I finally found it after getting home from work one night knowing it needed filling, flipped up the cover and being dark got my torch out to see better, that was when I noticed the steam passing through the torch beam rising from under the fan cowling. Never saw it in daylight and has been said before, the small amounts simply evaporated with the heat of the rad so no drips anywhere.
- (#7517) Dave B, 10 Jan 04 09:03
Saga so far, things seem to be getting complicated! I flushed the system with Holts 2 part flush and took it for the standard test drive as usual the gauge started to creep into the red near the end of the outward leg, stopped and checked the expansion it was about a third down from the top rather than full as before and although it looked like some coolant had been shoved out the overflow TBH I couldn't be sure that it wasn't coolant left lying around from when I refilled the system. However I noticed that when the gauge was creeping up my temp alarm didn't kick in (seems a bit of a wierd coincidence that it happened after the flush), I've tried adjusting the alarm level and can't get it to activate, yet the dash gauge is still reading, so I'm now wondering if in fact the gauge is reading correctly
or if a fault in the alarm box is causing it to read too high, although the "pattern" of gauge movement seems reasonable, I.E. it hangs around the centre mark while the vehicle warms up and only starts to creep up at around 30kM of driving. I didn't bother waiting the full hour or checking the level before I drove back, I just drove back with the passenger seat up and the heating full on and the temperature stayed down all the way back (speed kept to a max of 60, revs between 2000 and 3000). I left it overnight and in the morning the expansion had returned to the "Full"line and I needed 100mL of coolant (I've now started measuring it accuratly rather than guessing as before) to top the system up through the rad cap. I've now put a red bull can (simply because it's the right size to fit in the space) on the overflow to catch any lost coolant so I can measure it against what I'm putting in. SO while there seems to have been a bit of an improvement after the flush that could just be down to me taking more notice of the gauge and driving more cautiously?
- (#7517) Martin King, 11 Jan 04 07:54
If the level in the expansion tank reduced, then you will have lost some coolant. What happens is when the engine is cold it holds the most amount of coolant, with some remaining in the expansion tank. Once the engine is started, the coolant in the engine absorbs the heat, and expands. Once the pressure has reached 13psi, the radiator cap reacts and expels some coolant to the expansion tank, in order to maintain 13psi pressure. So when the engine is hot, there should be more coolant in the expansion tank. What can also happen is that when very hot coolant is expelled by the radiator cap, it passes from a pressurised system with a boiling point around 128°C, to a non pressurised expansion tank with a boiling point of 100°C. The result is the hot coolant instantly boils and turns to steam. The stem is many times the volume, 500% greater than the coolant, so the steam created forces some of the coolant out of the expansion tank, and lowers the level.
On the outward journey, everything was normal, but you overheated. The homeward journey was different because the passenger seat was up, the heating was on, and you limited the speed to 60 or below, and you didn’t overheat.
I doubt that the seat being up, made any difference, but with the heating on, you will have increased the cooling capacity, which might have prevented the overheating, or keeping the speed to below 60 could have prevented overheating. If the overheating is related to speed, then suspect the viscous coupling. If turning the heating on prevented overheating, then suspect a partially blocked radiator. Try the test run again with the heating off, and the speed below 60. If it doesn’t overheat, do it again with the heating on full, and drive as fast as you can.
- (#7517) dave Bright (Bournemouth), 11 Jan 04 08:34
i have had a similar problem to yours and found that allot of the emails on here are indeed helpful but don’t really make use of available coolant product technology and the fact that you may need to look else where to find answers
my van townace super- extra 1.8 auto with air-con always over heated heater blew cold all the usual problems aciated with over heating i did the same changed & number of things
1 change radiator cap
2 new water pump
3 various hoses changed
4 engine coolant flush
5 removed and refitted rad after rebuild
6 rebuilt cooling system with twin electric fan’s one manual switch and one with thermal auto switching
7. countless bleeding of the system
after all this i came to a number of conclusions
after purchasing mine initially i helped brother purchase a space cruiser essentially the same vehicle but no air-con this had a fit fitted by its owner who use to work for toyota he said all the early 1.8 models over heat ! he fitted an electric fan and added it even points toward this in the manual.
due to the position of the radiator for one thing when they over heat and cool down again it cracks the head this is probably what is causing your problem
on the town ace i got their was a air scoop (fitted to the underside of the vehicle to throw up air on to the rad’s) this was fitted to mine and makes a difference if yours has or you get fit it !
if you decide to take the bull by the horn and have the head take off repaired have the head welded and pressure tested or you can do what i did go halford’s and get some block repair. this is simply poured into the radiator and allowed to circulate with coolant all it does is find cracks and seal them ! it worked
although i have since found my mixture to be incorrect and causing the vehicle to run hot. so if your is a petrol model it worth getting the carb’s mixture checked
i hope this make sense and is of some use
- (#7517) Elwyn, 21 Jan 04 16:09