Technical More Overheating Problems - sob!

[alwold]

I'm gonna try and give as much information as possible here in the hope that someone can point me in the right direction!

I've got a 2000 Marea Weekend 1600! It appears to be overheating - in that the gauge will hang around at a 1/2 and then a steady increase will take it to the 3/4 mark. This increase can take as little as 5/10 seconds but sometimes longer! The gauge will the sometimes stay at 3/4, it will sometimes start to drop back to 1/2 - where upon the cycle will restart! It will also sometimes go up into the red!

I've found that if I turn off the engine (even when travelling) and then turn it straight back on - the gauge resets itself! It will generally be at 1/2 and then might slowly get hotter, but it does not immediately return to the red if at all!

I've replaced the thermostat, and double checked that I have no air blocks in the radiator (to my best ability).

The top and bottom radiator pipes are the same temperature after the engine has warmed up! The heating in the car works absolutely fine! I'm not losing any coolant, or have white smoke or mayo in the engine! The performance of the car seems to be absolutely fine in all other respects!


I'm slowly sinking into despair now! If anyone has any other ideas or pointers that would be great! The local fiat garage said it might be worth changing the sender unit - but I'm beginning to believe that they've got a load of surplus stock and that they are trying to offload it to me!

One other possiblity is the coolant pump - I think it's the original and the car has now done 65000!

Thanks for any help!

 

[OilBurner]

One other possiblity is the coolant pump - I think it's the original and the car has now done 65000!

If its the original coolant pump then I'll guess that its the original cambelt too. That being the case, at 65k miles you'd be wise to replace both (together with all other tensioners etc).

Does it make any difference to the overheating problem whether you are stuck still in traffic, or cruising at a steady speed? Or indeed whther the engine is working to take you up a long motorway hill when it overheats?

Have you tried a bottle of rad-flush?

Senders do fail, so your garage's advice is not unreasonable. Does the fuel gauge show similarly erroneous readings (concurrently with the coolant temperature gauge)?

 

[alwold]

Hello Again

Thanks very much for your help OilBurner, sorry I haven't replied earlier I've had computer problems - it never rains but it pours!

I've tried some of Halfords 2 pass Rad cleaning system - din't seem to make to much difference at all! Actually when the thermostat was replaced, the sender was also replaced by the mechanic - didn't notice at the time!

The Cambelt itself has just been replaced a few weeks ago, but the water pump was not done at the same time!

Some more info, I can guarantee it will overheat when climbing hills, either a steep hill or a steady climb. It will also overheat if I drive fast along country roads - keeping the engine revving in a low gear!

It's just come back from my mechanic's again - he can't believe that it could be the water pump as there is plenty of heat available via the heater and it would overheat a lot quicker. I don't know whether the water pumps can be less effective over time or partially fail!

The general belief in my family is that it is an electrical fault - not sure how to prove this! The petrol guage seems to behave itself - it varies in it's reading when you first turn the engine on as all fuel guages do!

It is possible to connect a different temp guage to the sender unit just to get a different opinion as to whether it is overheating at all!

The engine has been pressure tested and is fine - which rules out head gasket damage I've been told!


Any other ideas would be greatly appreciated and many good wishes will come your way.

Thanks

Andy

 

[polecat]

There is a known problem with bad connections on the guage, details here http://www.bravo-guide.co.uk/fix-a-bravo.htm

The water pump is also prone to fail between 80 to 100k and should always be replaced with the cam belt.

 

[BIG G]

Try runing engine with the exspansion cap off and the heater full on!! if you get no boiling air bubles coming up that rules out pressure problems (air locks)
try flushing out again then repeat above process or go for the water pump..

 

[jug]

There is a known problem with bad connections on the guage, details here http://www.bravo-guide.co.uk/fix-a-bravo.htm

:yeahthat:

a good bang with your fist often sorts the gauge out.

 

[mikiec]

I hope someone can help with this. My Marea TD75 SX Weekend has been fine (apart from a few niggles) but today on the dual-carriageway on the way to work, the hot air from the vents suddenly turned cold then I noticed that the temperature gauge (which normally stay belows half-way) was more than 3/4 of the way up, so I pulled over. When I popped the bonnet, I realised that it was low on water in the expansion tank, so I let the car cool down for about 45 mins and then drove it off the dual-carriageway and topped up the water. Everything was fine for the rest of the journey (about 40 mins).

On the way home, it was fine, even whilst stuck in horrendous traffic for over an hour. Then, just as I got onto the dual-carriageway going back the other way, the same thing happened... cold air, temp gauge rising. I pulled over, checked the expansion tank, which seemed warm but not hot, and let it cool down a bit. I set off again (no faster than 40mph cos of traffic) and it did the same thing, so I pulled off the road again and turned the ignition off, but the engine stayed on even with the key out, so I had to stall it to get it to stop.

I called out the recovery guy who was stumped but suggested that it didn't seem to be the water pump or head gasket, but was probably a faulty thermostat.

Does anyone have any ideas? I'm going to take it to the garage tomorrow so an idea of the cause would be useful.

Cheers

 

[richardwp]

:yeahthat:

a good bang with your fist often sorts the gauge out.

Certainly worked on my Marea and no prob since (seriously, this is what the dealer did and it worked when my temp guage went haywire. Wouldn't cure mikiec's prob though.)

 

[mikiec]

Update - After trying loads of garages nearby I eventually found one that could look at it today.

The consensus of all the garages I spoke to was that it was probably either a faulty thermostat or an airlock.

Anyhow, it turned out to be the thermostat which the guy was able to order and get the car back to me today... HOORAY!

Unfortunately, it seems that he got the wrong model (I should have known when he referred to my car as a Brava) and it's a Fiat dealership only part and he won't be able to get it in until Monday.... oh, and it's an extra £30 more expensive.

So, my plans for the weekend are screwed, and everyone's getting cheaper Christmas presents this year, but I should get my car back Monday (fingers crossed!).

 

[jug]

mikiec i'm willing to bet that your head gasket is leaking. a stuck thermostat cant make you lose fluid, and when a diesel wont switch off it is either the stop solenoid or because the engine is buring engine oil (through a head gasket leak). there is plenty of evidence to suggest head gasket leak so you need to do a compression test.

 

[mikiec]

Well Jug, it could be that you're right.

I was on my way to pick the car up tonight when the guy phoned me to tell me that the thermostat change hadn't fixed the problem and he suspects the head-gasket may be damaged.

To say I'm very p!$$ed-off is a massive understatement! If it is the head gasket, then that's one thing, but I'm really annoyed that he's diagnosed it as one thing and got me to agree to the work which hasn't even fixed it!

Does anybody know how much a head-gasket will cost to replace and how long it will take? I've been informed by a third-party that normally the cylinder head needs to be sent off to be skimmed as well.

There's no sign of oil in the water or vice-versa which I was told is what you need to look out for with head-gaskets.

Any advice would be very much appreciated.

 

[mikiec]

I'm still awaiting the results of the pressure test. Considering he told me that was what he was going to do in the first place, I'm still really annoyed with him.

Anyhow, I wondered if someone can explain to me how the heater vents work (inside the car), as in where the heat comes from and how any of the problems I've had would explain the sudden loss of heat from them coinciding with the rise in engine temperature.

 

[mikiec]

OK, the garage says there's a problem with the head gasket and there could also be a problem with a crack in the cylinder head. Guy reckons it'll cost between £550-750 to get fixed and that's before he's even taken the cylinder head off. Is this excessive? Can anyone give me some advice on this?

I'm not that mechanically minded and I've never been a in a position of having the space and knowledge to tinker with cars so I don't know whether the guy's taking the p!$$ or not.

The situation for me is that, if I get the repairs done based on what he's said, I'll have spent more on repairs in the six weeks of having the car than the car actually cost me to buy! Either way, I'll never get back anywhere near the money I've spent on it and I could have paid a full year's payments on a brand new car (the one I actually wanted) with warranty for the same amount!

 

[jug]

head gasket repair should cost you £170 in total, maybe £200 on a bad day. ask every local garage in your area and i'm sure you'll get a quote for less than £200.

a cracked head is a problem. generally whenever you do a head gakset replacement on an engine that has overheated you should do a pressure test on the head and then skim it if it is not cracked. if your engine has overheated to the point where the gauge touched the red then you may have cracked the head by overheating it too much, but this is very unlikely. it will mean you need to fit a scrapyard head, increasing the cost of repair by up to £75 (for a scrapyard head).

worst case scenario you pay £300. do not pay more.

the garage you are using have so far made mistakes than even a half competent DIYer would not make, plus they have quoted a stupid price for further work. i strongly suggest you take the car to different a garage and attempt to get some money back from the fool who fitted a thermostat.

I wondered if someone can explain to me how the heater vents work (inside the car), as in where the heat comes from and how any of the problems I've had would explain the sudden loss of heat from them coinciding with the rise in engine temperature.

the air is heated by the heater matrix. the heater matrix is a small radiator that your hot coolant passes through. when you lose coolant the heater matrix is the first thing to go dry because it is high up in the cooling system. once you do not have hot coolant going through the heater matrix you can not heat the air at the vents. that should be a warning sign that you need to switch the engine off immediately, although your temp gauge is the best warning. always keep a close eye on the temp.

 

[mikiec]

Thanks for your help jug.

I've reached the point where I have no trust left in the car or garages, so it's currently sat outside my house without a new head gasket but a brand spanking new thermostat - WOOHOO!!! NOT!

Anyway, I've learnt my lesson that unless you can fix these things yourself or know someone who can (and won't rip you off), then second hand cars aren't worth the aggro. I'm sure lots of people will disagree with me, but I've read too many scary stories across the net in the past week to make me realise that people like me (IT guy who doesn't like tinkering with cars too much) are better off getting a brand new car. Ask me to install a new hard drive or replace the fuser unit in a laser printer and I'll have no problems but cars are a different matter.

Good luck with your cars guys.... I'm off to find a new one with a nice long warrranty!