Peugeot 306 D Turbo overheating problems...

July 10, 2006 6:39 AM

Peugeot 306 D Turbo overheating problems...

My 1995 peugeot 306 has started overheating. The temperature gauge is shooting up to over 90, whereas it used to keep itself a constant 70-80. When it gets over 90, the thermostat obviously kicks in, some loud fans come on and the temperature goes down a little bit.

The other weird thing is, when I turn the heater up to max and turn the fan on, only cold air comes out the air vents, even if the engine temp is hot. It just doesn't seem to make sense.

I've checked the radiator, and it's full of water up to the MAX level... please hope me!

posted by derbs to travel & transportation (16 comments total)

IANAM - Water pump? Stuck thermostat?
posted by toastchee at 6:50 AM on July 10, 2006

Ah, a broken water pump would sort of explain it... do water pumps normally have a fuse i could check?
posted by derbs at 6:52 AM on July 10, 2006

Low antifreeze level is another easily checked possibility.
posted by Mitheral at 7:11 AM on July 10, 2006

Dang it, posted not previewed: What I meant to say is: low antifreeze level is an easily checked possibility.

When you experience the overheating immediately pull over and check the level in your expansion tank. If it is at the point of overflowing then you could have a bad head gasket that is pressurizing your cooling system. Also check your expansion tank when cold to get a base level.

However 90 ain't all that hot, what have the ambient temperatures been like during the periods of over heating?
posted by Mitheral at 7:17 AM on July 10, 2006

It's summer at the moment in the UK, so it's been quite warm. It never actually overheats, because the fan kicks in, but it is annoying because it used to maintain a rock solid temperature instead of getting caught in this annoying thermostat loop...
posted by derbs at 7:36 AM on July 10, 2006

is it full of water or antifreeze/coolant? you're actually supposed to have a 50/50 mix of antifreeze and water in it, and not just straight water.
posted by mrg at 7:44 AM on July 10, 2006

does it actually know that the coolant is 50/50? Is there some sort of sensor?
posted by derbs at 7:49 AM on July 10, 2006

Mitheral - if the poster is in the UK it's likely 90 centigrade, which is not good...

we had the same problem a while ago, except we had steam coming from the bonnet. We suspected a broken head gasket (expensive!!! might be better to write off the car!) but it turned out just to need a new radiator (cheap!!!). Best get it down to the garage ASAP.
posted by altolinguistic at 8:36 AM on July 10, 2006

I second toastchee: sounds like a water pump or thermostat. Water pumps are generally driven by a belt off of the crankshaft. I'd check the thermostat first, though, because it's easy to do and cheap to fix. Pull it out of the car, put it in boiling water and measure it, then try it again with ice water and you'll be able to see how far it opens. If the difference is less than half an inch or so, replace it.
posted by Daddio at 8:58 AM on July 10, 2006

"when I turn the heater up to max and turn the fan on, only cold air comes out the air vents, even if the engine temp is hot"

Which means coolant isn't getting to your heater core. The flow is either blocked or isn't powerful enough to reach it. The cheapest possible solution is to try and have your radiator flushed.

This probably won't fix the problem because you mention that you are using water in your radiator. Don't use water in your radiator. If you have been using water in your radiator for 11 years then it's likely that your radiator is coated in minerals that were contained in the water and has a severely reduced flow; it also means that you have to replace your radiator.
posted by 517 at 9:03 AM on July 10, 2006

There's no fuse for the water pump, if they go bad, you'll have conditions like you describe or they will leak.

My diesel Peugot overheated and the head gasket blew. You need to take care of this asap.
posted by toastchee at 9:23 AM on July 10, 2006

Could be the thermostat - which is a dead easy fix. If its stuck closed it would explain the temp change and the lack of heating - your car wouldn't necessarily be circulating hot water from the engine to the heater matrix to heat the car or the radiator to cool the engine down, depending on the system. Daddio sets out how to check, but be careful with the housing and the gasket- they're easy to break.

Might also be clogged water channels in the radiator - esp if you don't use anti-freeze- if you take it to your garage they can pressure test it to check. (Mitheral is slightly confusing - no antifreeze can cause corrosition, which could cause the heat increase - but in and of itself it wouldn't cause the problem.)

If the radiator needs replacing its an easy job and shouldn't be more than an hour's labour (I'd have thought - not familiar with your car) and relatively cheap bits - or its well doable at home (even I managed it!) It goes without saying that IAMAM.
posted by prentiz at 9:53 AM on July 10, 2006

There are weep holes in water pumps which usually leak when that component begins to fail. This is mostly on (American) domestic vehicles I've seen though.

The heater in my car (Audi A4) wouldnt get hot, even after replacing the thermostat. There is a special procedure for bleeding air from the system that i had to follow. No problems now.
posted by kableh at 10:07 AM on July 10, 2006

Oh, I'd just add that if you remove the thermostat for replacement, you can throw it in a pot of boiling water and it should open up. If it doesn't, you've found your culprit (maybe).
posted by kableh at 10:08 AM on July 10, 2006

derbs writes "It never actually overheats, because the fan kicks in, but it is annoying because it used to maintain a rock solid temperature instead of getting caught in this annoying thermostat loop..."

You could have a bad rad, either an external blockage or damage or it could be be corroded internally. This could reduce the cooling capability of the rad to the point that the rad fan has to come on. When you remove the rad cap can you see the cores? Do they look clean or are they plugged up? Check the fins on the outside looking for extensive damage or places where the fins have come away from the tubes.

altolinguistic writes "if the poster is in the UK it's likely 90 centigrade, which is not good..."

He wouldn't be complaining of overheating at 90F. 90C =195F or where most production engine thermostats fully open. Until temperatures start cresting 95 you don't usually have a problem per se on modern cars especially if ambients have been in the 35-40 range.
posted by Mitheral at 10:26 AM on July 10, 2006

Thanks for the answers everyone. I'm still unsure as to the real cause, so i can't mark a best answer yet. I'm going to investigate the thermostat and water pump, but I think it'll have to go down the garage. At least I know what i'm talking about now though... so thanks!
posted by derbs at 2:13 AM on July 11, 2006