Over heating Again

[spoofer]

Finally had the money to repair my project MR2. Blown head

Bill of parts below
Spark plus £20'73
Plug leads £56.40
Dizzy Cap £52:82
Rotor Arm £11.10
Timing belt kit £128.08
Coolant £7.46
Head overhaul £446.50
Labour £211.50

Total £934.77

Garage owner assures me, the head has been fully rebuilt, and i.e. skimmed valve oil seals stem seals and seat cuts.

I got the car back on Friday. Only driven short distance so didn’t get warm. Plus no MOT or Tax. It’s been sat on the drive over the weekend.

Just started her up ran to temp. No heaters few mins later the temp of the scale. Steaming from the expansion bottle. Annoyingly these were the sypmtoms of the blown head. I even had a sniff test down before I took the car in.

So am I looking for another problem, or bad work man ship? Or just re bleeds the coolant system out

[JDM-MAT]

I would bleed the coolant mate.

[Steve-O 2007]

are you sure the Thermostat isnt broke and stuck closed? worth checking that

[ashley]

Is it a turbo or NA?

+1 for bleeding it again and checking the thermostat

[gazrev1tubby]

Sorry to say you got raped for that bud - a replacement engine would've cost half that

Anyway, back on topic.....

I would re-bleed the coolant system, they're inherently bad to get all the air out - just make sure you set the heaters to hot and get the car as level as possible.

[spoofer]

its a NA lump,

i looked at replacement engine, but thought better the devil i know. going to give the guy a call tomorrow. let him sort it.

everything other than the thermo have been replaced. work does look neat under the lit.

im hoping its just bleed it again. cry

[spoofer]

the heater were set to hot and car on flat drive way

[Driftlimits Performance]

How much for the head rebuild!!! We do a full rebuild, dip, clean, skim, vac test seals etc etc for more like £200.

sounds like it needs a bleed.

Oh, and a timing kit for £128!? You can get the belt for £20 and the 2 bearings for £20 each. Even with a new tensioner it's not that much.

[sjm1984]

Who was the garage in question?

[spoofer]

place called Smithy Garage

in sheffield south yorkshire.

car just been lifted back to him, so fingers crossed

[Rogue]

You're in a chicken and egg situation. Most overheating issues left unchecked will warp the head... which will cause the car to overheat. It's possible that you may have fixed the effect and not the cause.

The obvious thing that's not been mentioned yet is to make sure that your radiator fan is switching when the car is up to temp. While the car is moving, generally you have enough airflow to keep things cool, but when stationary you have nothing. *Any* MR2 left idling with no fans will overheat after a while.

The other thing that I would recommend is to pressure test the coolant system (there are specific kits for doing this). Quite often there are pin-hole leaks or cracks in the MR2's pipework - particularly in the heater hoses that run above the petrol tank - that are so slight they only show up when the system has pressurised. This means the coolant leaves the system as steam - often without leaving even a tell-tale drip. A pressure test will tell you if the system has integrity or not, and force coolant out in liquid form making it easier to find.

[spoofer]

Rogue
Thanks for the reply

When I first got the car, the rad was shot, since been replaced. But I have never been able to bleed the system out. After running for a while temp goes off the scale, and steam from the expansion bottle.

With gas sniff test the fluid turned green.

Garage sent the head off to Sheffield Engine Services. Were the above work was done.

Just spoken to the garage just said the thermostat hasn't been changed

[Rogue]

The thermostat will only cause the engine to overheat if it is stuck closed. The simplest test for this is to warm the car up to temperature and see if the pipe under the bonnet leading to the radiator is warm. If it's not then the coolant is not circulating.

If the thermostat is stuck open then the car will take a very long time to register that it is up to operational temperature - if it does at all.

If you've never been able to bleed the coolant properly then it sounds like you could have an airlock. Simple enough to sort out and a garage should be able to do this without any issues.

[spoofer]

Rogue

All the fans have been working front and rear.

Yesterday the engine bay fan came on but the front rad was stone cold. So hoping air lock or the stat.

I did notice below the stat is a green block connector. That someone has crimped spades into. But the circuit appears good

[Rogue]

The engine bay fan is a totally independent circuit to the radiator fan.

[spoofer]

sencer on the lid i believe. front rad fan has been on in the past, but that was before rebuild

[spoofer]

just got the car back heaters blowing fine,

alternator seems bit xxxx, battery charge now very good and dash light fickered.

on the way back the temp scale dropped to the bottom , then cold air in the vents

[Canopus]

I would still suspect an air lock of some kind as if the heaters are now blowing cold there is no water in the heater.

Temperature sender unit a bit more worrying as if suddenly dropped to cold it would suggest no water there either.

Wait until cold then remove the pressure cap in the engine compartment and check the level of the coolant. If not visible this would suggest an air lock.

Believe there is an article on the knowledge base how to bleed the coolant - its not hard to follow and may help you solve the problem, but they can be a bit tricky sometimes.

I replaced the entire coolant on my car some years ago and did not have a major problem with bleeding the system albeit I had to do it a couple of times.

Sometimes, if cold, if you take the pressure cap off and run the car at idle it helps to clear the air - it is important to have the heater controls on hot as the MR2 has a valve which admits water to the heater matrix and if this is not fully open air will get trapped.

Hope this helps

Geoff

[kennym]

The thermostat will only cause the engine to overheat if it is stuck closed. The simplest test for this is to warm the car up to temperature and see if the pipe under the bonnet leading to the radiator is warm. If it's not then the coolant is not circulating.

If the thermostat is stuck open then the car will take a very long time to register that it is up to operational temperature - if it does at all.

If you've never been able to bleed the coolant properly then it sounds like you could have an airlock. Simple enough to sort out and a garage should be able to do this without any issues.

I wouldn't question rouge on mr2's I haven't done an engine on one and i dont even know were the stat is or how its oriantated.....

having said that i am a garage owner & have built many engines.......I do recall a problem which i have found oftern on a ford pumas where even after a bleed you can get an air bubble behind the stat.......it somtimes proves very hard to remedy as the stat stands verticaly....... the air bubble doesnt heat up like the coolant & consiquently the stat doesnt open.....however when you test it the stat works fine....

the cure it to drill a small 2mm hole in the top end of the stat this is enough to let the air pass through but not effect the job the stat was intended for..........just a thought..........

[spoofer]

guys thanks for the replys.

coolent levels appear fine, the

heater valve under the front bonet whne tampered with it the martix got hot. but i can still hear air bubbling about behind the dash.

as the for the stat in thinking its been removed or jammed open.