[Mk2] [NA] MR2 Issues - Baffled

[mrmark80]

Hi All

Hope you can throw some ideas my way with this, it is baffling a couple of us who are trying to fix my car. Apologies if the description is a little on the essay side, but it's important you get all the facts.

The problems started not long after I bought the car in June 2007. I took it on a run to Sheffield via the M1, Junction 26 to 31 to be precise. No problems so far, but when I came off the motorway and pulled up at the traffic lights, the temp gauge went through the roof and the rad cap blew (as it should in these situations). Steam pouring out the back of the car. Pretty impressive looking, but not what I wanted to be happening. The blowers in the cockpit were also blasting cold air when set to hot. The car lost coolant, and I had to stop and let it cool at a friends house before I could top it back up and get things working again. The same happened on the way back down to Juntion 26 the following day.

So, we replaced the water pump, the thermostat, the timing belt, the filler neck (the neck that the rad cap screws onto), and the rad cap itself. We bled the system several times, and filled up with correct coolant. Still no joy. We then realised that the water was leaking from water bypass number 1, due to rusting. So we replaced that aswell. This was around christmas time a few months ago.

Ran it out the motorway again, still overheats. I must stress that the car only overheats when driving flat out for 45 mins on the motorway at 70-80 mph, I can hammer it round A+B roads to my hearts content, no performance loss, nothing.

So thinking it may be a blockage, we put some 'Bars Flush' through the cooling system. We also 'smoked' the car with Redex, through the spark plugs and by using the fuel injector cleaner. Cleaned it out nicely, still overheats on motorway.

Now we have been trying to work out what is wrong here for a few months now. I have been assured that because the car is running fine for the rest of the time, it is not the head gasket. I am having this tested next week because I am not convinced, but we shall see.

So last Monday I was driving home from work, and after around 5 mins, the temp gauge shot through the roof. No blow out though, and upon investigation, engine temp was fine. Once I got home, I did the old paper clip to the diagnostic port check, and got the error code:

22 - Coolant Temperature Signal - Whenever a short circuit or a circuit detactment in the coolant temp sensor is detected - Could be either Sensor, Wiring and Connectors, or ECU.

So, I have reset the ECU and the error has gone away for now, and the car hasn't done it since. I wanted to see if it was a one off or not, so I will check again this weekend to see if any error codes are back.

Bizarrely, this morning, it did something it has never done before. Upon cold start, it instantly idled too low and the whole car was shivering. Once I revved it, it idled about 1800rpm and was fine. Idled nicely when warm aswell, no searching (never has done) and temp gauge was bang on half way.

Until I realised the fans were blowing cold air when the blower temp was set to hot. The temp gauge shortly after plummeted from half way to three quarters of the way, and hot air then instantly started blowing through. Sounds like an air lock to me, but I am certain I got all the air out of the system the other day.

Soooooo....any ideas folks? I am intrigued at what the head gasket test will bring next week, but other than that, I am completely stumped. The pipes in the engine bay pressurise nicely, the rad cap is tight on, no loss of coolant through that. So what the hell could it be?

I am stumped. Maybe the expertise on this forum could shed some light of where we go next.

Cheers all.

Mark

[mrmark80]

I'd also just like to add that I dont think my engine bay fan is working. Is there an easy way to test this? I haven't seen or heard it come on for a few days now.

May change the fuses just in case!

Cheers for any help you can give.

Mark

[ChrisW]

I'd also just like to add that I dont think my engine bay fan is working. Is there an easy way to test this?

Pull the plug off from the temperature sensor on the underside of the engine lid. Turn ignition on and the fan should come on.

Is your radiator getting hot? If not then your thermostat could be stuck in the closed position.

[mrmark80]

Cheers Chris,

I shall try that, but not sure what the temperature sensor looks like or where it is? Could you give us a very brief guide to the location?

This learning curve gets steeper......

[ChrisW]

It's bolted on the bottom side of the engine lid - it's the only sensor there so you can't miss it

[matt_mr2t]

Leave it unplugged as well, more cooling is always good

As for your over heating problem, not really sure mate. I gues the thermostat would be the natural place to start tbh.

[derryt]

this might be a silly suggestion, but is the inside of the car, specifically the footwells under the carpets wet? some of the symptoms you've described happened to my punto and it turned out the heater matrix was fubar

the symptoms i had were cold blowers, even on max temperature, or it would get slightly warm but not much, and it would start to overheat, it did start idling funny as well towards the end but i dont think that was the heater matrix

I'm not a mechanic so probably dont really have a clue what I'm talking about but might be something worth checking anyway?

[ormzy]

Just a query, are you sure your bleeding the cooling system correctly? Are you hanging two lengths of pipe attached to the bleed points on the Rad and heater? And when doing the bleed is your heater in the hot position?
Sounds like it still has air in the system.

if your sure your bleeding it right, then from cold, start it up, and let it run. Find the pipe that runs from the thermostat housing to under the car to rad. The temp needle should rise just under half way before that pipe gets really hot. if that pipe doesnt get really hot that you cant hold it then your stat is stuck shut.
If the pipe gets hot and the Rad is getting hot all the way down to the lower pipe then the Rad and stat seem fine. Are your front cooling fans comin on? If your head gasket has gone between cylinder and and water holes then its going to generate excess pressure, possibly steam from exhaust, loss of coolant.
Best see what the pressure test shows.
HTH

[mrmark80]

Thanks derryt, I will check this tonight when I get home and let you know.

With regards to engine bay fan, unplugging the sensor worked a treat. I shall keep it unplugged until I source a new one and then try that.

ECU has just been reset so will monitor how things go and will keep all informed.

Cheers for all your help!

Mark

[matt_mr2t]

Thanks derryt, I will check this tonight when I get home and let you know.

With regards to engine bay fan, unplugging the sensor worked a treat. I shall keep it unplugged until I source a new one and then try that.

ECU has just been reset so will monitor how things go and will keep all informed.

Cheers for all your help!

Mark

Just leave the sensor unlpugged, having it on all the time is better.

[mrmark80]

Matt, does the sensor I have unpluged control anything else other than the fans?

[Slarty]

Matt, does the sensor I have unpluged control anything else other than the fans?

No, it just controls the I/C fan.

Sounds like the classic symptoms of a blown head gasket though. The gasket usually fails between the combustion chamber and the coolant jacket. This then over pressurises the coolant, resulting in over heating and the rad cap letting by to relieve the pressure.

Might not be, but it's something you might want to look into.

[mr2guy]

hi mate, just read your post and i have to say it sounds exactly like the problem i had with mine, would run fine for half hour or so just pootling about, but any running at about 60-70 ph and would overheat, turned out that the headgasket had hairline cracks around the piston and coolant valleys ? (not a mechanic so appologies for non technical terms)this was pushing air at pressure into the coolant system stoping the engine from cooling properly, but a new headgasket,bolts,and clean up, plus 500 quid and all is sweet once again, sorry to say it but your H/G sounds fubar'ed, good luck mate

[regovdaro]

Hi mate i also have the same problem as you, me and trickster pulled out my engine cleaned it all up and replaced the head gasket with a metal one but we could not see any problems with the old one, put the engine back in and the water pump leaked so we replaced that. It was fine for a few runs and its starting to over heat again, i havent replace the stat yet but also now the engine stalls and if i try to turn the engine over it struggles as if the pistons have expanded and causing fto much friction.

anyway all i can say to you is do a compression test on the coolant and see if it holds pressure and also do a compression test on your cyclinders. it could be that the head gasket is dead or maybe like what i think is wrong with my car the piston rings are goosed and are expanding to much and the more revs you make the more fiction causing more heatforthe coolant to handle.
hope this helps

[-:[KM]:-]

Yup, get a sniffer test done. You need to eliminate the HG first of all as it sounds the most likely to have gone, then it will be a process of eliminating things one by one.

Where are you?

[Tomiam]

So, I have reset the ECU and the error has gone away for now, and the car hasn't done it since. I wanted to see if it was a one off or not, so I will check again this weekend to see if any error codes are back.

Bizarrely, this morning, it did something it has never done before. Upon cold start, it instantly idled too low and the whole car was shivering. Once I revved it, it idled about 1800rpm and was fine. Idled nicely when warm aswell, no searching (never has done) and temp gauge was bang on half way.

Mark,

I appreciate Im running a 3vz-fe (V6) but when I reset my ECU it takes a little while for the car to work itself out again.
ie: First time I reset the ECU, I started the car up and the engine stalled instantly. For about 10 mins, it also liked to cut out when driving along and then stopping at traffic lights.
Once Id driven it for 20 mins or so it was perfectly fine.

Dont know if that helps put your mind at rest about the low idle.

[mrmark80]

Guys, thanks for all your posts. Here's an update on an interesting but frustrating weekend.

Since friday night, the car has been overheating on short journeys, boiling coolant in the expansion tank. These journeys have been 15 minutes, a few of them less. It is also blowing constant cold air through the vents, regards of the temp set for the blowers. The rough idle upon startup has still been rearing it's head (it is only on startup aswell, once I stick the revs on, it goes away), but here's the weird bit.

I bled the air from the radiator valve today, and from the heater matrix. Lots of air in there. Water is now definately running through these systems, and the pipes leading from the rad cap are pressurising. I have topped up with correct level of coolant and water. Last night I took the car for a blast and hot air was blowing through the vents, was out for half an hour with no problems. I came back to the car this afternoon, started her up and the idling startup issues were back. Cold air was constantly blowing through the vents again, and within ten minutes of running, the car overheated.

And here's a massive factor in this problem I reckon...the heating pipes were still pressurised 14 hours after last switching the engine off.

So, we bled the car correctly again, and refilled. The car has now lost it's rough idle on startup, and heat is coming out the vents. I am going to run the car out tonight and pressurise the pipes, and see if they are still holding pressure in the morning.

To me all this is pointing to the head gasket. I am going to book the car in for it to be checked at some point this week, and I am fully expecting it to have gone.

BTW, no water in footwell guys, and since resetting ECU I have down over 2 hours of driving, on and off. So I would assume that it would of sorted itself out with regards to fuel mapping etc.

I shall update when i know more.

Cheers all

[regovdaro]

check the rad to see if both pipes at either side are the same temp, cos you might not be losing coolant at all it could be a cracked block and pressure is getting it your coolant system and this will cause the expansion tank to blow or steam to past through the expansion tank thinking you have lost coolant.

The reason i say check your rad temp on both sides is because the pressure can also stop the coolant from flowing around the system causing it to boil u in the engine

[raptor95GTS]

as said previously get a sniffer test done, if the head gasket has gone this should be spotted by the sniffer test

[mrmark80]

Morning All

Sorry about the delayed update on this post, had alot of progress in the last few weeks due to the hard work of a good friend of mine!

Head Gasket had gone so that has been replaced. So has the idler and many other parts (dont have my list with me, but will let you know so others are aware what to look for). Needs a new exhaust which will be changed in the coming weeks. Also had a rock solid blockage in the pipe under the cylinders. No water was passing through. I assume the was the main cause of the over heating! Pipe is now clear, we hope the cylinders are ok.

Not tried it on motorway yet to test overheating (although it was doing it on short journeys before).

Back on the road last night, we have been having some idling issues. The car starts first time, but sits at 1000 rpm straight away when cold and the car judders and jumps all over. When warmed up, drives fine but when you decellerate to a stop, at traffic light or to park for example, the car tries to stall. The revs drop to below 500 rpm and the whole car shakes. It is shaking when idling too, doesnt sound too bad.

The timing has been done and later tonight we are going to adjust the tickover. May just be set too low.

Anyone else experienced the idling problem one their engine has been put back together?

MC