Please help.
I have a j reg town ace 2ltr turbo diesel 4x4. My main problem has been over heating. I have had a new radiator and a thermostat after two episodes of the temp gauge hitting the roof. Now i have a strange problem my garage cant sort out. When I turn the engine off after any length of journey, steam is coming back through the pipe that leads to the exspansion tank and boiling the water in there. The temp gauge is normal though. Anyone had this problem.
Also my 4x4 button has no light and doesnt engage the 4x4 when pressed. I thought it maybe a fuse but couldnt see one in the fuse box.
Also the air/con doesnt seem any colder than normal air passing through the vents, does it need re-gasing.
Please help

- (#9565) Matt Moore, 11 Jul 03 10:13

Hello Matt

When you turn off the engine, the water pump stops circulating the coolant. The engine still has a lot of heat in it, and the now stationary coolant can become to hot and start to boil. As it does it forms steam within the surrounding coolant. Now when water turns to steam, the volume increases a lot. This causes the pressure within the cooling system to increase, and as it does, the radiator cap reacts to the increased pressure and releases some coolant to the expansion tank.

One important thing here, is that the expansion tank is outside of the pressurised system. Water under 13 psi can be as hot as 117°C and still remain liquid. If the radiator cap lets some of this hot coolant out, it will suddenly be well above the normal boiling point, and will boil instantly, turning to steam.

The cause of this problem is that the coolant is boiling at too lower temperature, and this will be due to reduced pressure within the cooling system.
The solution may be as simple as replacing the radiator cap, or finding a leak on your system.

Hope that helps
dave Bright

- (#9566) dave Bright, 11 Jul 03 11:53

I shal;l print your reply and take it to my garage. Are you a mechanic?
If not how do you know this?
This has been a 8mnth problem and i have been looking to replace my mpv. You may have solved it in less than two hours.

- (#9567) Matt Moore, 11 Jul 03 12:47

Matt. Dave's reply is right on the button and should be more than helpful to your mechanic/garage. However, in my opinion, your engine is getting too hot anyway. On my Masterace 4WD I should be very alarmed to see the gauge register much above 95, in any driving situation and, even when stopped when, as Dave rightly says, the heat within the engine raises the temperature of the static coolant. If you look on Ace Answers you will see much about modified thermostats and checks which you can make. I run on the recommended Toyota thermostat, ie, the one with the better suction type valve and a 30 mm opening aperture but, through the summerI have three 3mm holes, acting as a bypass, drilled in the thermostat flange. I change this, later in the year, for my "winter" stat, which has only one 3mm bypass hole. Coupled with a Durite gauge, instead of the "always in the middle, then suddenly into the red " Toyota gauge, I never have any of the problems which you, unfortunately seem to have had.

- (#9568) John Davis, 11 Jul 03 13:45

I am not a mechanic no, but I have been puzzled by this cooling system for some time, so I have read all the postings on Ace Archives and applied a little bit of logic. To coin a phrase, “I am merely C”.

As regarding your 4x4 problem, checkout the archives this Ace Answers website as there are a number of fuses and relays all over the place that could cause your problem. For air conditioning, find a local specialist in yellow pages, or yell.com. They should be able to diagnose the problem.

Glad to have been of help.
dave Bright.

- (#9569) dave Bright, 11 Jul 03 14:07

Oh! not sure wat happened there, it should read
To coin a phrase, “I am merely standing on the backs of giants”.
- (#9570) dave Bright, 11 Jul 03 14:10

I own a 1989 Royal Lounge 2.0 EFI and I recently had a overheating problem which started with a burst hose or so I thought. I live in Merseyside and on a trip to Glasgow a few months ago I had the radiator cap replaced because of a minor water loss problem. After having the cap replaced all was fine until Fathers day when I took the family for a day out to Blackpool. On route to Blackpool the temp gauge started to show sighns of running hot but I put this down to a combination of weather (it was a hot day) and my driving speed (I was doing 80mph). But on the way home the temp gauge started to climb rapidly and I had to pull onto the hard shoulder. I discovered that a heater hose had burst which I thought was down to the age of the hose but I later learnt that it was'nt. With the help of some duck tape and a container of water from a friendly Police patrolman we managed to limp home. I replaced all the heater hoses and radiator hoses and thought that all was fine until I had to do a fifty mile drive and the temp gauge started to show that the Townie was running hot yet again. I was near a Petrol station so I pulled in and had a look to see what the problem was this time. On inspection I could see water pouring out from under the vehicle so I raised the front passenger seat to have a closer look. Water was pouring out of the expansion tank overflow hose which in turn was draining all the water from the cooling system. Again I managed to get my self home by stopping every few miles to top up the coolant. I was unsure as to what the problem could be so I posted a question on this site and got a reply sugesting that it could be the radiator cap. I have replaced the cap and all is now perfect. The temp gauge neddle now stays just below the middle of the gauge. I found that the cap that had been fitted by a Toyota Dealer in Glasgow was the wrong type and was causing to much pressure in the cooling system.

- (#9571) Bill Dickinson, 11 Jul 03 17:57

If your mechanic has'nt managed to solve the problem in 8 months - then surely it would be wise to use another
If you post your area someone may be able to recommend a local garage with townie experience
Regarding the 4wd I think this is operated/assisted via vacuum - so would check your vacuum pipes around the box - regarding boiling coolant - have you got a decent anti freeze mix to raise the boiling point - would suggest check for air locks is the pipes also. Has the system has been thoroughly flushed through both ways with a hose to remove sediment?
Also ace answers cites some thermostats sticking in their housings - having recently done mine (hiace not townace) I noted that aftermarket non original stats are offset - sticking a half inch ext' bar down the thermo housing explained why and allowed me to align correctly - (if you read my recent amatuer posting on stats you will see that I am not a toyota stat convert - though I did try) - other reasons may be soft hoses (collapsing under vacuum).
Although the toyota pressure cap is supposed to help bleeding air I have found that on my vehicle it cannot be relied on totally so don't assume there is no air lock (on mine manual massaging of the top hose is essential)- you did'nt mention if the pressure cap had been renewed in the last 8 months, so consider this also - Is your pick up tube in the expansion tank attatched and working properly
Also, is your fan operating correctly??
Is the head gasket ok (air in the coolant)?
If you are not one for permanent mods then for the sake of 30-40 uk pounds you could buy a multimeter with a temp probe - as the engine is in the van there is no prob routing wires etc. and it can be removed in seconds - I found the best place to put the probe end was to wedge it in a gap by the threads of the original temp sensor, seal with clear silicone and secure with a cable tie - the wire then just slips under the engine cover seal and into the cab - you could also use the multimeter to check your 4wd switch - I have always believed that most tools have paid for themselves within a couple of uses and therefore (depending on your point of view) end up costing nothing
Hope you get it sorted soon
Chris

- (#9572) Chris Turner, 11 Jul 03 18:25

When I hear of repeated, delayed, boiling-over problems, I'd go for airlocks caused by re-filling too hurriedly. Re-fill REALLY slowly after draining the system. Trickle the coolant in over a period of 10 to 15 mins. When I've done this I've found that after running the engine the coolant (cold again) is still up to the filler neck and the expansion tank still has the same amount in it - which suggests to me that there was very little air trapped inside the system. That's very different from what happens if you fill it quickly.

- (#9573) Dave Mason, 14 Jul 03 5:24

i have been reading with some interest about all the possiables of overheating,i had very much the same thing happen to me and was a problem for well over 2/3 years,after 2 engines,and 1 new head i have got down to my core problem of overheating and all the damage that go,s with it,first i found a good garage,i had a new head fitted+mot(£1200)plus i had both rads take out and recored(£325),the top rad had afew small leaks but the real problem was the bottom rad was totally blocked(the cores are much smaller in size then the top rad)i also got new rad cap from main dealer (part number 16401-63010 £16.90+vat)i now check my oil weekly and now check my water level by looking into expansion bottle level,i feel if after renewing rad cap the overheating is still a problem then have them both out and get them recored

- (#9662) dennis, 15 Jul 03 9:08