Mr2 Advice Needed Please

[chris100]

Hi All

This is my first time on the site, I hope I have posted this in the right forum!

My mr2 Mk1 has a problem, at the weekend in overheated, boiling water was getting into the collant overflow bottle, the temperture guage was off the scale. I checked and no water was getting to the radiator, I turned the heater on and it was cold.

Then the temperture dropped and the heaters started to work, so water was flowing again. I am no mechanic but I have a few ideas, 1. thermostat on its way out, valve or air block, or Head GAsket Failure can any one else think of what could be happening or rule out any of my theories?

Cheers

Chris

[chris100]

just to add...

it continued to over heat on and off, i had to keep stopping to let it cool down and other times it just stated working.

[Jimlad]

Just hope all that overheating hasn't caused the head to warp and the headgasket to fail!

[chris100]

True! hope not, if the head gasket has gone or damaged would there be a drop in performance? also I drove it for twenty miles the next day to get it home and the temperture didn't move above normal, would this indicate the head gasket is ok?

[T600]

I think it's probably a good sign that h/g is OK.

Sounds like you might have had an air lock that disappeared once you switched on the heater.

If the car seems to be well now, with no loss of performance and no over-heating, then I think you've got away without any serious damage.

Good luck.

Tony

[Jimlad]

I wouldn't be so sure. I would still get it compression tested all the same. Check your levels, ie water/oil, make sure it's not using any then hope your HG is ok.

[msherry21]

Sounds like an airlock to me in the coolant system, if it happens again i'd say bleed the system.

[chris100]

I will book it in for compession test, thanks for the replys. is it true the head gasket can go with no sign of white sludge in the oil?

[Jimlad]

The HG can go with little signs at first. Get it checked.

[System~G]

I will book it in for compession test, thanks for the replys. is it true the head gasket can go with no sign of white sludge in the oil?

Don't waste your money... A compression test on these cars does not always show a failed HG. The only way to tell for sure is a "sniff test". Although some garages will conduct another test using dye, but again the dye test is not always 100%

The cooling system on the MK1 is over engineered and not very complex once you understand exactly how it works.

There are temp sensors around the system that work together to give you your gauge reading. You have 1 by your thermostat, 1 at your radiator and one near your throttle body (I may be missing another out - can't remember off the top of my head).

The symptoms you describe definately indicate there is air in the system and possibly a leak too. The heater matrix is the highest point of the cooling system and is prone to trap air, although it's not uncommon for air to get trapped in the throttle body either, but you'll get revving issues if air is trapped there.

If air gets traped in the water ways of the block/head or continueously passes through the engine will overheat and potentially warp the head or worse the block. Head gaskets can fail without the head or block warping if caught early enough.

The best thing to do now (before driving the car any distance) is to top the system up with either tap water or Ethylene Glycol based coolant (do not use alcohol based coolant). You will need to "burp" and bleed the system thoroughly. Keep an eye out for any leaks on the system (water dripping onto the ground etc...). Read "Chapter 3 - Cooling, Heating, Air Conditioning" at the following link http://www.mr2mk1club.com/repairsindex.html before starting, becuase getting it wrong will waste your time - it's not difficult, but can take a long time - I have sometimes spent over 2 hours just bleeding a system when doing it right. There is a lot of technical info and help on the MK1 site. The site is a bit messy at the moment, but is currently being re-designed.

If you are thinking about self maintaining your MK1 it will also be an idea to get a copy of the BGB (the manual Toyota mechanics use). PM me for a copy if you need one or if you need any help don't hesitate to ask on the forums.

[chris100]

[Hi

Thanks for all the replys, I have had the coolant replaced and the system bled through, the garage also did a dye test which said there was no leaks and the dye test showed there where no leaks from the head gasket. I drove the car for numorous short journeys all seemed fine. However I have just drove it a fair distance and the overheating started again. the temp needle went right off the scale, steam bubbled into the over flow and the heating stoped working. then suddenly needle droped to normal levels and the heating started again. it did this several times. i could drive it for several miles then the needle would rise.

I think my next step is to look at the thermostat??? can I drive the car with the thermostat disconnected?

cheers all

chris

[System~G]

The only way to test 100% one way or another is a snif test for headgasket failures.

When you say steam bubled into the over-flow... Do you mean the expansion bottle was empty? Or was it full and bubbling?

When the system was bled was the heater turned to full and fans on full?

Just out of interest, how long did it take to fill and blead the system?

Are there any swishing or gurgling noises coming from behind the centre console?

It doesn't sound like the thermostat TBH. It sounds like the system wasn't bled properly or there is a leak the dye test was pointless as they usually are. They don't really work on a MK1.

Does the radiator get hot after say 15 minutes of driving?

If so, the your thermostat will be working. Although if there is muck or crud caught in the thermostat, then it could remain open, but this shouldn't cause over-heating.

I have driven one of my MK1's for a couple of weeks without a thermostat without any problems.

I don't mean to draw dark clouds over the topic, but you really need to determine where the leak is asap as if you don't already have a head gasket failure, you will shortly. Also if the gauge start climbing above half way, pull over and switch the engine off imediately - don't let the engine get so hot the gauge goes off the clock.

Check all hoses & connections and each of blead/drain !Removed!/valves.

I replaced all my tention clips with proper Jubilee clips. Don't bother going cheap route on these as cheap jubilee type clips are crap, buy only the Jubilee brand. You will need three sizes so get an example of each you will need and find the suited size as if you go too large they won't clamp the hoses properly.

I also replaced all the rubber O-Rings on all the blead/drain !Removed!/valves - you can get all these from Toyota for around £5.

Also do not use an radseal or coolant system sealers - it just messes up the MR2's cooling system further.

Keep us posted, let us know how you get on