overheating shortly after starting

[Smokey Boyer]

Yesterday, and for the first time, my 290 S3 overheated while sat in traffic. I had been driving around for about 30 minutes and the car had ben fine, parked up to go to a shop, and when I started up and drove out of the car park, ended up sat in a line of traffic at the exit for about 5 minutes. I could hear a funny noise, which I assume was water bubbling in the expansion tank. Temp gauge was reading a just over the 92 mark, which is high for my car. Turned the heater on hot, and it went straight back down to normal, and the bubbling sound stopped instantly.

Today, started the car up from the garage, drove slowly out to the main road and ended up sat in a line of traffic after about 10 minutes of the engine running. Noticed the temp gauge was creeping up higher than normal, again heater on and everything back to normal.

Both times the car then continued to run fine without the heater, even when stood in traffic for a short time.

The only thing I can think of that has changed with the cooling system, is that I took off both caps from the expansion tank and swirl pot last weekend to check the levels. They went back on the same place, and it was confirmed at Newark Kit Car Show, that they were on the correct way. Yes, I dared to ask that question and open the debate....

I already have a ali radiator on the car. I am new to TVR and the S3, is there something obvious I am missing or doing wrong? I now remember reading something about bleeding the water system - have a I caused a problem by taking the caps off ?

Any advice on this please from the resident forum experts.

[pk500]

could be thermostat sticking! if turning on heater cures the problem !

[Peter M]

Don't Thermostats normally stick open ? It sounds more like an air lock in the system. I would make sure there is no air in the radiator by opening the bleed screw on top. Then run the engine with the swirl pot cap off and squeeze the hoses to the rad and see if any air bubbles come out in the swirl pot, and then top up the water and put cap back on and fingers crossed. Leave the heater on HOT while doing this so the heater rad has flow through it. Blipping the throttle might also help push any air round and out the swirl pot.

I remember when I drained my system, there were loads of air locks for a while.

Good luck

[Spanish S2]

Forgive my ignorance, but is the fan kicking in, you have not mentioned it!

[The Beaver King]

I had a similar thing happen a year or so ago.

Started the car, got 20 minutes down the road and noticed the temp gauge was climbing above the normal level. I pulled into a car park and switched it off, waited for it to cool down, then popped the cap off to check everything.

There was nothing obvious and the fan was operating as normal. My only conclusion was that the thermostat had gotten stuck and failed to open. I whipped that out and drove home. I tested it on the bench (the old boiling water in a cup test) and it was indeed the thermostat.

New one ordered and in, job's a good'en

ETA - I can't picture the cooling layout in my head at the minute, but does the heater matrix feed come from the swirl pot? I'm just trying to remember if you would still get interior heat with the thermostat stuck closed? I think you do...

Edited by The Beaver King on Friday 5th July 14:05

[tvrgit]

First things first. It was fine before, and now it isn't. Before you go jumping all over the cooling system, start with what you did. Are the caps both sealing properly? Have the rubber seals been damaged? Have you dislodged corrosion on the necks to prevent it sealing? If it can't seal, it won't pressurise, and then will boil at a lower temperature.

Then check if it needs bleeding - unlikely though unless you had to put a lot of water in.

Another thought - you didn't overfill the swirl pot, did you? Despite what the book says, mine runs with the swirl pot over an inch from the top, and the expansion tank as good as empty. If I put more in, it boils it off to that level, then runs for months with no change.

Then, and only then, should you accept that maybe, by coincidence, the thermostat has started to stick, or some other unrelated fault has arisen.

Start with the "what could I have done" stuff first.

Edited by tvrgit on Friday 5th July 16:52

[mep12345]

I agree with Andrew, including the water level thing. An inability of the system to pressurise will cause localised boiling in the hot parts of the engine and therefore reduce the cooling effect in that area making the issue worse and creating a downward spiral and possibly even vapour locking the section which then has the same effect as an airlock (long winded explanation of thermodynamics and surface effect available if you want).

I note you don't dare say which way around the caps are to open up the debate :teasing everyone smilie as I have a posh alloy expansion bottle so don't give a s**t anymore:

Above comment before Norm tries to draw me out from cover again



Mark

[Smokey Boyer]

Just gave it a run home from work, after resealing the caps on both the swirl and expansion tanks. Given how hot it is today, the car ran as it did a week or so ago with the temp not getting all the way to 90 (close but not there), so perhaps it was just a poor seal. Will keep a close eye on it though. Waiting for the car to cool down and will go and check the levels again.

Many thanks for the advice - exactly what I needed.

The previous owner said do not touch the swirl pot and keep the expansion tank about 2/3 full. Does that sound right? The expansion tank level has never changed. I know from the comprehensive service history that both caps are less than a year old.

[mep12345]

I used to use Andrew's rule above, basically bleed the system and fill the swirl pot, expansion tank empty when cold. Run it and keep bleeding and topping up the swirl pot until no more needed and water starts to flow out top of swirl pot as car warms. Then stop the car and let it cool down fully. Then re-fill the swirl pot leaving the expansion tank empty. Put both caps on (I won't specify which way around ) and go for a drive, let the car get fully warm and "throw some water out" then let it cool down again and check level was about 3/4 up the swirl pot with expansion tank empty. Once it had done this it would run fine for miles.

I don't do this anymore though as I now have a full swirl pot and a half full alloy expansion tank but my system is now about 1 litre bigger than the standard and works really really well - the custom expansion tank was one of the best £70 I've spent.

Tried to upload a picture of new expansion tank nut the beta uploader doesn't seem to be working

Mark

[Barkychoc]

Has the new rad been bled? Given your issues it may want doing again anyway. Small tap at the top of the rad at one end.
Be careful if its hot.

[steve j]

Have you checked the locking lugs on the caps ? It was pointed out to me that unless the lugs hold the cap on tightly, air can be drawn into the system when the engine cools.

[Smokey Boyer]

The cap on the expansion tank is very tight. The swirl pot cap is loose by comparison - I will see if it can be made tighter will a little persuasion. I will see how it goes over the next few drives.

Am I right in thinking that any excess water simply boils away or overflows out of the expansion tank, leaving the system to find its own level?

[Griffinr]

Smokey Boyer said:

The cap on the expansion tank is very tight. The swirl pot cap is loose by comparison - I will see if it can be made tighter will a little persuasion. I will see how it goes over the next few drives.

Am I right in thinking that any excess water simply boils away or overflows out of the expansion tank, leaving the system to find its own level?

The seal on the swirl pot cap is very important as it allows the system to suck water back from the expansion tank as the engine cools. If all is working properly there should be no air in the engine or rad as it wil be forced out when hot through the expansion tank.

Rob

[Top Gear TVR]

As the actress said to the bishop;' it's probably the seal of the cap' - steve j had something similar in spa last year, and I had it when I fitted a pants new stainless swirl pot with lugs as strong as aluminium foil.

I would check the thermostatic cap seal on the swirl pot, look for bubbling / leaks all after a proper bleed and burp on the system. Don't forget to play with Max's little tap too.

I have an alley rad and it take years to even warm up. Another bypass plumbing story...... I need a man with a tig welder for that mod.

[Smokey Boyer]

I read in the Steve Heath Bible last night that the water pump and alternator do not kick in until the engine gets to 2000 RPM. I knew about the alternator, but not the water pump. That might explain why I had a problem with my car that was already hot when started in the car park, and not pushed beyond 2000 RPM as it sat in traffic.

[Griffinr]

Smokey Boyer said:

I read in the Steve Heath Bible last night that the water pump and alternator do not kick in until the engine gets to 2000 RPM. I knew about the alternator, but not the water pump. That might explain why I had a problem with my car that was already hot when started in the car park, and not pushed beyond 2000 RPM as it sat in traffic.

The water pump is working as soon as the engine is revolving but will of course shift more water as the revs go up and also when the thermostat opens. With a cold engine it circulates through the bypass hose.
Rob.

[wizzer]

Just had similar problem. Found the cooling system was loseing pressure, pressurised water boils at a slightly higher temprature. New pressure cap on the swirl pot cured it straight away. Just an suggestion but a cheap cure. Also vent the rad. may have a small airlock which is what could cause the noise.

[Smokey Boyer]

Another run out in the car yesterday, and it looks like refilling the swirl pot has cured the problem. I assume I introduced or already air lock.

[glenrobbo]

Glad you seem to have it all sorted.

Just as a footnote, three of us with S1's found that the temp gets into the red zone during spirited ascents of tortuous alpine passes even with the heater on full blast ( not what you want in 30 degrees ambient temp! ), but cools on the way down whilst your brakes are on fire!
We kind of got to accept this as normal!

Austin has used about half a teacup of coolant in the whole trip. ;smug smiley:

Sorry, just couldn't help mentioning it

Edited by glenrobbo on Thursday 11th July 09:23

[Rower]

Smokey Boyer said:

Another run out in the car yesterday, and it looks like refilling the swirl pot has cured the problem. I assume I introduced or already air lock.

I have quantity of home made rubber seals that will solve the swirl pot issue , send me your name and address via my profile and I will send you one free and for gratis !