over heating at motorway speeds HELP

[Itsallicanafford]

Hi all

my brother has a 106 rallye and we are experiencing over heating issues on motorway driving but it runs as normal in town???

its a bit of a head scratcher but iv read that it may be a thermostat stuck open issue, does this sound likely ?

the system has been flushed to the best of our ability so im hoping there are no blockages in it

any advice would be much appreciated as we have a Trackday on Wednesday and trying to sort it before then

thanks

[Itsallicanafford]

Chaps,

Thanks for the replies, much appreciated. I'm picking up a new rad 8am this morning (ordered 4am, £50 new, in stock half a mile away from my house, you've got to love running a dirt common car like a 106!). Quick rad change, off to the track, let you know how we get on.

Cheers!

[Itsallicanafford]

Ok, did the rad change but still have the issue. I think it must be the water pump so going to have to get that done at a garage...going to get to the bottom of this!

[Itsallicanafford]

LarJammer said:

What are the symptoms when it overheats?

Thanks for the reply.

It's no problem at all in traffic or on B roads, but anything over say 50 mph and the temp rises, at motorway speed the warning light comes on. It's never boiled over, there no steam etc. I was thinking it's not a head gasket as that would overheat in traffic as well? Maybe the water pump is just not working well enough to cop with higher loads, lost an few impellers maybe?

Any advice gratefully received

[Itsallicanafford]

Hello chaps.

As a quick round-up, here are the steps we have completed so far...

1. Flush - new coolant
2. Flush again - new coolant
3. Flush at local garage (they were replacing a top mount) - new coolant- new rad cap
4. New thermostat - flush - new coolant
5. New radiator - flush - new coolant
6. new 02 sensor - new airflow temperature sensor - new fan sensor, air filter (bit of a long shot but would eliminate any poor running issues)

So step 7 is new water pump and will have the cambelt done. Unfortunately this is beyond us so it's going into the garage.

Step 8 will be the head gasket.





Here a shot if the temp gauge. Interestingly, this is as high as it goes when at motorway speed, slow down and it will drop down again slowly, speed up and it climbs quickly.

As always, any advice greatly appreciated.

Edited by Itsallicanafford on Sunday 29th May 14:00

Edited by Itsallicanafford on Sunday 29th May 14:08

[Itsallicanafford]

FordPrefect56 said:

You seem to be throwing an awful lot of time and money at this but only a miniscule amount of thought! From everything I can see so far you don't actually even know whether the engine is overheating and haven't tried even the most basic of tests to find out. The warning light shouldn't come on until the engine is close to melting and certainly not when the needle is still in the normal part of the gauge. On my car the warning light is set for 125C. Your manual should say what it is on your own car. Anything from about 118C upwards probably depending on the system cap pressure. The radiator fan should be on long before this. Maybe from somewhere between 105 and 110C.

Sit the car on the drive. Rev it gently to get it hot fast. Does the radiator fan come on? Where is the needle on the gauge at this point and has the warning light come on. The fan should be on long before the warning light and before the needle reaches the red. Does the fan cool it back down quickly? Does putting the heater on full help with this? Is the radiator hot all over? Does properly hot air come out of the heater? Does it use any coolant at all? Have any of the hoses been re-routed from their correct positions or is all the cooling system still standard? Are there any high spots in the hose runs where air could be getting trapped? Can you get it hot enough to create steam or lose any coolant before the fan kicks in? Does the warning light only indicate excessive temperature or is it also designed to indicate low coolant level? Did you ever think to check the manual to find out?

It ain't rocket surgery. Just fairly rudimentary tests and thought process before lashing out on things that weren't faulty in the first place. So far it could just be a dodgy temperature sender triggering the warning light too soon and it's never overheated at all.

As ever, many thanks for the reply, much appreciated.

Too be honest, we have done most of the above tests, but I will pick up on a few points:-

If you sit on the drive and rev it, it wouldn't bring the light on, it really seems to be only under driving load and above 50mph.
The fan does come on but I thought it was coming on quite late so changed the sensor in the rad. The rallye does has an interesting fan design (might be common with other 8 valve TU engines) in so much as it has one fan and an empty carrier for a second). The fan being on or off really doesn't seem to touch the water temp.



I know of some Rallyes which have a second fan retro fitted, I'm going to PM the owners to see why exactly.

The heater works fine, good heat.

The original rad was hot all over.

The pipe work looks in it's original configuration, the pipes all look ok when cold or hot.

The manual states the temp gauge should sit in the normal area (the picture I posted earlier shows it at the very top of normal.) the manual states the light comes on when the car is over heating.

In regards to if it is actually over heating, apart from the light, when you stop you have a nice puddle of coolant forming under the car as it escapes through the filler vent. This happens when the rad has not been over filled. Also, in the 1500 miles I have done in the car, it never used to do this, water temp was good , registering around half way after spirited driving.

As far as the spend is concerned, I'm less worried about this than loosing a precious track day as with small kids these are my life line to sanity! The 106 really needs to be 100% fighting fit as although it gets driven at least once a week for my 50 mile commute to keep it in shape, on track days it's going to typically do 300 road miles and 100 track miles so it needs to be in first class nick to cope with this. Also, a lot of these parts I've changed I would file under preventative work, you should have seen the state of the 02 sensor! All in I think I have spent £150 odd on parts as they are all standard 106 so cheap.

I think the cam belt/ water pump change is prudent now as I should have done this when I purchased the car 6 months ago as there is no record of it being done as the car has no history.

Thanks again for the ongoing help, much appreciated.

[Itsallicanafford]

Hello, the symptoms have been the gauge and also the puddle of coolant on the floor after every use.

But it is true we haven't done any formal diagnostics apart from the checks highlighted above, what would you suggest?

[Itsallicanafford]

Many thanks for the reply. I must admit it's starting to look like a HG failure but it's booked into a citroen/ pug specialist so they can have a good look at it. If i get time I will do a compression test.

[Itsallicanafford]

so, to update this, its in the garage...

Its not the water pump as they have had that off and it looks OK. Its also not the head gasket, but the heads coming off as they think it might be a blockage in the waterways in the block...

[Itsallicanafford]

FordPrefect56 said:

Itsallicanafford said:

so, to update this, its in the garage...

Its not the water pump as they have had that off and it looks OK. Its also not the head gasket, but the heads coming off as they think it might be a blockage in the waterways in the block...

This is crazy. There are no waterways in the block small enough to get blocked in the first place and even if there were it would overheat all the time. The block's just a big open tub. There's nothing in it you need the head off to check anyway. Did they do a proper pressure test? That's the first step. If there's a leak anywhere then the coolant will boil at much lower temperatures than it should and then start blowing out of the vent which you say it does.

A pinhole will do it or just a single hose clip with a bad connection.

thanks for the reply chap, i will certainly ask the question...

[Itsallicanafford]

Right then...pick the bones out of this then

[Itsallicanafford]

Yeah, that's the working theory, they said that even after a few minutes on tick-over the head was getting very hot so they have assumed that there is insufficient flow. But, the correct part would appear to be similar if the image on 106parts in accurate...



A new gasket is coming in tomorrow so they can check to see if the existing one was incorrect...

The waterways in the block and head seem far larger than the holes in the gasket, looks alittle odd?

[Itsallicanafford]

Thanks Dave for the response, very much appreciated. My apologies in advance if i use the incorrect terminology below, as you can tell i am a layman when it comes to the internal working of engines!

The mechanic did say that they thought the head gasket wasn't particularly tight when they removed it, could coolant have been passing into each of the cylinders and causing the cleaner areas on the pistons? The car was abit Smokey, if you revved it hard it would puff out a bit of blue/white smoke but i had that down as worn valves seals (which the are going to replace now the head is off) and generally a worn engine as it has done 90K miles. It would be especially bad if you left it to idle for a while and then accelerated.

The head is going away to be checked and pressure tested so i assume that they will skim it if required.

Many Thanks

[Itsallicanafford]

thanks for the responses chaps.

Could i ask a quick technical question. When hot (or very hot as i was looking after a run with rad. fan on) should the coolant be flowing through the radiator? I pretty sure the answer should be yes but if you look into the expansion tank the water is totally static? Would you not see any movement in this coolant in the tank, being the design of this is directly linked to the rad rather than a pipe fed header tank design.

[Itsallicanafford]

Ok, update...









So, the head is back, it was found to be pretty straight but it has had a very light skim.

The car is at a pug/ citroen specialist, they are currently working on 4 DS's an SM as well as C6's. Talking to the mechanics, they found that when they were starting the engine, the head was getting very hot very quickly. When they turned the engine off they could hear the coolant bubbling in the block but nothing was overflowing out of the rad. This is why they beloved that something was stopping the coolant circulating into the head. You can see from the head gasket there was a small blockage but nothing too serious. The theory then was the head gasket was incorrect, but a new one has been purchased and this looks very similar. The idea is to refit the head and re-test. After that, if the problem is still there, they have suggested opening up some of the coolant holes in the head gasket? I'm not too sure if this is a good idea?

The head had been skimmed before, if too much has been removed, would this alter the compression ratio and could this lead to additional heat being generated in the head?

Again, any comments gladly received.

[Itsallicanafford]

Chaps, thanks for the reply. I've called them and told them not to touch the gasket, I didn't like the sound of that either. However, they have had another look in the cooling system and although the water pump was new, the fins from the last one were still in the system and causing a blockage.

Bit frustrating as I suppose the head didn't need to come off then, could have saved a few quid if so.

But I suppose the car is new to me and had limited history so I now know that the water pump, cambelt, head gasket are all new (as well as the rad, thermostat, O2 sensor!) Plus, the smoking on acceleration should be sorted by the new valve stems.

Going back together on Monday so fingers crossed...will let you know!

Thanks again for the continuing advice, much appreciated.

[Itsallicanafford]

So, these were found in the engine waterways...

When the water pump was last changed they obviously didn't question where the missing fins had gone.

Picking the car up on Thursday so fingers crossed we are back in business...

[Itsallicanafford]

...at the FOS at the weekend. The car is back and working well, i'm not sure what actually fixed it but i suppose by changing everything something worked! No more smoke on acceleration any more either...

Thanks again for all the help and comments, much appreciated!