Peugeot 306 - overheating problems

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piblet
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Peugeot 306 - overheating problems

Post by piblet »

Hello Chaps

I’m new here but after some desperate help. I hoped somebody might be able to give me some guidance.

So, I bought a 1.4 Meridian 1998 (S-Reg) 306 about a month ago now, after I needed a car quickly when my last one was written off (got swiped by a van, but that’s another story). It came with 12 months MOT. I’ve probably driven the car around 500-600 miles since I’ve had it so far.

When I got the car, I noticed that it was running quite cold. I also noticed that on a few occasions after getting hot in traffic (90-100 degrees) it spurted water/coolant out through the pressure release valve. I topped up again with coolant, and thought that perhaps the pressure cap was dodgy, so replaced that (old pressure cap had a rubber seal around it that looked worn; new one was straight from Peugeot dealer and without a rubber ring seal, but seems to fit snugly).

This didn’t seem to sort out things, so I took the car to a local mechanic, who flushed out the coolant and replaced the thermostat (again, with one that I bought myself from the Peugeot dealer). He told me (Worryingly) that the thermostat had been removed, suggesting that there had been some pre-existing problem and I had been driving around without a thermostat. He was clear that the system needed refilling in a special way (which I’d already read for myself on these forums) so that air locks didn’t build up, and he seemed to know what to do (although to be honest I didn’t sit and watch him do it!). The car sat in the garage for at least 45 minutes idling without going much over the 90’c mark at all. There were no signs of coolant loss at all. Note, that he refilled the car only with water (not coolant) because he didn’t want to lose the coolant if it spurted out again.

Next day, I drive the car to work (about a 10 mile drive, but involves dual carriageway). Noted that the car appeared fine in traffic (i.e. sat around 90’c), but when I went up to speed (60mph plus) it started heating up further (i.e. 110-115’c). This appeared to happen particularly when driving up hills, and the car would cool down on the other side, particularly if I let it coast. I thought this was really odd as the car would surely be cooling down with the air flow.

There are no signs of mayonnaise under the oil cap, no obviously unusual exhaust fumes, no obvious loss of power when driving, but there does appear to be something of an oily film on the top of the water/coolant (although the mechanic who looked at the car said that he’d never seen a 306 without such a film). The coolant does appear quite dirty (reddby/brown colour). The heater does get hotish when the car is warm, although interestingly I noted that it seemed not to get hot when it was driven at speed: I’ve checked the water since (when cold) and it seems the level is about right and I don’t think there’s any significant water loss (although will need a bit more time to be certain).

So, I have the following questions:
a. Should I be worried?
b. Any ideas about what’s gone wrong?
c. Any ideas about what will happen if I keep driving it like this? (I haven’t seen it go over 115 degrees, i.e. below the upper limit of the temperature gauge, but I don’t like the look of the symptoms).
d. Any ideas about how I might get it fixed? (I’m no mechanic, and if anybody can recommend anybody good in Essex I’d be keen to hear from you). And how much might it be likely to cost?


With MANY thanks for any replies,

Peter

P.S. The car does have A/C, but it doesn’t work (light comes on, air doesn’t get colder)
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Post by spider »

Welcome.

The fans should cut in at 90c on the gauge :)

If its overheating when under load (such as hills) it points towards a failing water pump (the impellers can come apart) or a blocked / blocking radiator.

These symptoms arent always easy to see at idle as its not under load and they may be adequate for idling.

Running it at > 90 to 100 really is bad, its likely to blow the head gasket.


Regarding filling, yes they have to be bled out (same as your central heating radiators) although this is quite easy anyway really, there's only a three points (some times just two)

I'm assuming your mechanic did not notice any leaks so we can rule that out. Also I would assume they made sure the cooling fans came on at 90 on the gauge (mid point)

Regarding A/C , its likely to have no gas in it (the light will still work but nothing else) as the sensors will not enable the system if the gas pressure is too low, typical points to fail on a 306 are the A/C pipes where they pass along the bottom of the radiator area, this problem is highly likely to NOT be related though to your overheating issue.

My initial thought is to change the water pump and have the radiator inspected (but you said he flushed it out, so that is probably OK)
Andy.

91 205D-Turbo, gone but still missed
02 106D, TUD5B, gone but not really missed apart from the MPG
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Post by piblet »

Andy,

Thanks for replying so quickly - I really do appreciate it.

As for the fans, this was a problem that was considered at first. I haven't actually noticed the fans cutting in (or not) so there is a possibility they also aren't working (I guess in addition to whatever other problems there are). I had assumed the speed of the car would cool it down negating the need for cooling fans at speed. I hadn't considered the water pump though, thank you. Looks like there may be more than one thing... and let's hope I haven't broken the head gasket, if it wasn't already gone!

Thank you

Peter
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Post by spider »

You're welcome.

You are right, in that coasting downhill will reduce the temperature a bit (it will actually rise slightly then go down) , which makes me suspect its not receiving enough cooling (radiator or water pump) :)
Andy.

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Post by myglaren »

I'd second Andy's diagnosis of a failed water pump.

If it were the radiator fans then as you have suggested, cruising at over 40mph has sufficient airflow due to the ram effect so they are largely superfluous.
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Post by piblet »

Thank you for all the replies. Just to update:

1. Got a second garage to look at it - they did a block test - the liquid stayed blue, he told me suggesting head gasket was okay on at least one side.

2. Asked them to look at water pump or blocked rad - they said they felt water pump was working fine as water was going around as it should do (but presumably they didn't look at the pump itself, given that involves removing the cambelt) - also felt radiator was getting hot in all the right places. Essentially, they appeared to be as clueless as I was (which I suppose is reassuring that I've looked at all the right things!)

3. Second garage said it "might" be a head gasket leak between oil/coolant, as there was some evidence for oil in the coolant - but would this cause these symptoms?

Do the water pumps commonly fail on the 306? Does anybody know if the impellers are metal or plastic?

As I said, car is fine when it's sat idling but only gets hotter (around 100'c) when driven at speed or up hills...

Thanks so much for replies

Pete
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Post by spider »

Not sure on the material used on the impeller, however they do rot in some cases, hence me suggesting it as it fits your symptoms.

There is enough movement at idle and low speed to still circulate the water anyways, which is why you do not notice it at idle.

I forget the proper term for this, but hot water can in some cases actually circulate without a pump, once its moving. Not suitable for motor vehicle engines though like this, obviously.
Andy.

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Post by myglaren »

You are thinking of convection :)

It is not unknown for the impeller to come adrift from the shaft, leaving the impeller static and the shaft spinning away merrily, doing nothing.
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Post by spider »

myglaren wrote:You are thinking of convection :)

It is not unknown for the impeller to come adrift from the shaft, leaving the impeller static and the shaft spinning away merrily, doing nothing.
Thanks Steve. Yes I had momentarily forgot the correct terminology.

I think the problem is at idle there's enough circulation ( ! ) to not display any symptoms really.
Andy.

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Post by myglaren »

You could very well be right there.
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@piblet: any progress with this?

Post by xhtml »

I've got exactly the same problem on a 306 HDI, although only intermittently, and have posted detailed symptoms to see if they tally with your experiences.

Usually it occurs if the car has been driven for a while (radiator heats up normally), then stopped for at least 15 minutes and driven again, after which the radiator (sometimes, though not always) remains cold, despite the engine getting so hot that the STOP light comes on. And when this happens, one of the radiator fans rotates at top speed, although the inlet and outlet pipes to the radiator remain tepid. (On a single 25 mile journey to work, no problem appears and the radiator is always hot at the end of the trip).

The coolant is not leaking, and the radiator & thermostat have been replaced, with the mechanic ensuring no air blocks. The dashboard temp guage shows about 75 deg (ie normal) and the internal fan blows hot air as expected. There is no evidence of a blown gasket (eg dirty coolant, loss of coolant, steam out of exhaust).

Next step for me is a new water pump, but I'm not holding my breath. Could this be an earthing problem?
Its strange that there only appears to be a blockage (or lack of coolant flow to the radiator), when the engine is hot.

Any other diagnostic advice would be much appreciated.
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Post by spider »

The HDi's can be a pain to properly bleed, I would get it re-checked. I've had the odd one that would not bleed up properly for ages, took a few attempts, you really need to feel the pipework as it starts warm up to be sure as well when you think you have bled it.

Assuming its not an airlock, then it points towards your thermostat being jammed shut (easy to test, I know its new but its possible to buy faulty new parts for any car) / water pump failing

It is possible as you say its running at 75c , if you have a fault with your aircon that can cause the stop lights to come on and the fans to run at full speed (I have seen this once and it was a HDi too) , typical cause (assuming A/C is generally sound) is the relays infront of the radiator area, corroded pins. Caution: The fans are permanently live! , keep fingers clear if playing with the relays.
Andy.

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Post by xhtml »

Thanks Spider.
I'm not sure I understand the significance of the relays. I'd assumed the fans were being influenced by a temp sensor, though not the one displayed on the dashboard.
Corrosion - implying open circuit? Or an internal relay fault?
I've noticed after a few miles from cold, there's some high current switching going on as the main lights and dash displays dim momentarily over a period of a few seconds. Then it seems to stop but may occur later in the journey, becoming noticeable if stopped at traffic lights as the engine speed also drops around 50 rpm.
BTW the A/C has been out of gas for the last 15 months. The cold radiator problem has only been present for the last couple of months.
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Post by spider »

They are controlled bit the Bitron effectively. More about this later.

The dimming will be the initial loading of both fans coming on at high speed, that's normal.

Regarding relays, usually corrosion on the pins or water into the relays themselves.

They are about where the badge is on the front panel but on the panel not the bonnet obviously :D (the clips will come out with care and this panel comes off) and you can see them, typically three. Caution: the fans can start (even without the ignition on) if you poke around with the relays, fingers + fans = not good.

I'm not 100% sure about the bitron on a 306, 406's have a brown sensor screwed into the thermostat housing (you will probably have this too) and a control module up behind the glovebox (on a 406) , your's may be in the same place.

An "overheat" signal (which can be caused by the faulty sensor of faulty wiring) will illuminate the stop light and switch the fans to high speed, one relay actually controls this (I think the middle one, if you unplug it the fans will start)
Andy.

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Post by piblet »

Xhtml, interesting to hear your experiences, they are different to mine.

I have "solved" my problem by removing the thermostat. I only use the car for a 10 mile return trip to work every day and at the moment, it seems to be fine. Car now runs cold (i.e. no heating, a bit of a pain of late in the cold) but I didn't feel that spending the money on a cambelt/waterpump was money well spent given the myriad of other minor faults with the car (I really was sold a lemon).

I read about people drilling a hole in the top of the thermostat to allow the air-lock to dissapate... I tried this but to no avail, unfortunately. Water, in my case, was spurting through relatively nicely through both bleed valves regardless and apepars to be moving around the system nicely, but clearly not nicely enough!

(On a related note, I was quite pleased with myself -- the garage told me that the heater matrix was faulty... however they clearly hadn't bled it properly as onceas I let it get to temperature with the bleed screw off and water coming out it warmed up quite nicely!)

I don't think I've damaged the H/G ... I've driven over 1000 miles now in the car and nothing has changed. It runs fine (but cold) with the thermostat out, and runs fine with the thermostat in until you take the car up a hill or drive it above 50mph! I have been wondering about driling holes all around the thermostat just to let a bit more water through (like a restrictor plate) but also to get the heater working slightly!! A bit of a bodge, but frankly if the car blew up tomorrow I wouldn't shed too many tears.

Good luck with yours
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