BX overheating

mak224751 · Post by **mak224751** » 25 Oct 2005, 13:29

I have replaced some water hoses because they had perished and split. I thought this would solve the problem of the car overheating. unfortunately it hasn't. I also had to replace a smallish belt which fits over two pulleys on the nearside of the engine. Does this turn the water pump as i think the belt might be slipping. By the way the car only overheats when driven over 2500 rpm (approx 70mph). Any ideas would be appreciated as I am sick of doing 120 miles a day and not able to go over 60mph. The car is a 1.7 Turbo Diesel Citroen BX 17 TZD Turbo.

Thanks

fastandfurryous · Post by **fastandfurryous** » 25 Oct 2005, 14:22

If this isn't the beginnings of a blowing heag gasket, then it's most likely a clogged radiator.

Pull the rad out, and backflush it (with a pressure washer if you can!) and see what comes out.

Also, put one of the hoses back on the loose rad, and see if the radiator will take a decent flow of water through it. I'm guessing you'll find it won't.

I had a similar problem on a car many years ago, and after cleaning the rad out (with Viakal, it was full of limescale!) it turned out that it needed a new thermostat, as it was then overcooling..... arse.

bxbodger · Post by **bxbodger** » 25 Oct 2005, 14:56

By the way the car only overheats when driven over 2500 rpm (approx 70mph

You must have had the special government speed restrictor installed under cover of darkness......

Seriously, though, what do you consider to be 'overheating'- does it cook itself in the way Dennis Weaver's car in 'Duel' did , with steam all over the place, warning lights flashing, etc, or is it that you have a temp gauge and its just reading a high number??

The small belt you mention drives the alternator only-the water pump is driven by the cambelt, which is toothed and lives behind the plastic cover on the left of the engine as you look at it with the bonnet up.They normally leak when they start to go - water starts dripping from behind the cambelt cover although its not immediately obvious thats where its coming from.
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vanny · Post by **vanny** » 25 Oct 2005, 15:54

Erm, by the description of 'near side' of the engine id sounds more like the belt your refering too is the HP belt (next to the battery) and you might want to get it sorted if its slipping as it will start to cause you all sorts of hydrualic problems!

I've found the guages to be spot on on these cars, and as suggested the usual cause of overheating is a dead thermostat or a blocked radiator! Its worth swappin gout the thermostat as it will only set you back around £6 and an hour max to change it! The radiator is quite easy to remove and while your back washing that out, you may as well back wash the engine from the thermostat housing as you go. The haynes explains it all! (and can be found in various places online!)

Might want to get yourself membership of www.bxclub.co.uk and call out international rescue!

jeremy · Post by **jeremy** » 25 Oct 2005, 17:34

Thermostat will be fun - its huge and a different shape I think you will find. When I did mine 2 out of the 4 studs broke and I had to drill them out.

So - soak everything in a releasing agent and be prepared for trouble when doing the job. Incidentally mine still runs cold most of the time with the new thermostat and the heater is good but no better than it was before.

vanny · Post by **vanny** » 25 Oct 2005, 18:34

i got lucky and only one of my bolts head snapped on the old 19rd. I just bit the crap out of it and eventually got it to spin off while destroying the thermostat in the process, though i didnt think this was actually that common??

I know have the later 'xantia' style thermostat housing and it pretty much falls off (the one with the bolt in the fuel filter)

Stewart(oily) · Post by **Stewart(oily)** » 25 Oct 2005, 19:02

Sounds like a clogged radiator to me, my cooling fans only come on twice a year, usually in stop start traffic, once rolling its extremely rare for the TZD to get hot enough to need fans.
Stewart

citronut · Post by **citronut** » 25 Oct 2005, 19:40

in normal conditions the fans only cut in at slow runnig or stationery,whilst engine is hot,as when driving faster there is enough air flowing through the rad,the first thing i would do is spend some time bleeding the system properly,firstly remove rad cap and the plug in the top N/S of rad,now withe heater control turned to hot,put coolant in untill it comes out of the plug hole and stops sinking,re/fit the plug and remove all the other bleed valves,continue putting coolant in untill it comes out of these bleed points,if it dose not then start the engine and run it untill coolant dose come out of these points,now replace the bleed valves and rad cap,cotinue runnig the engine till the fans cut in,when they cut back out gently remove rad cap,if coolant is calm its sorted,if its not calm run it up again till the fans cut back in and folow the last instruction again
regards malcolm

mak224751 · Post by **mak224751** » 26 Oct 2005, 12:34

The fan only comes on when the car overheats ie over 2500rpm and STOP light comes on and red lights by temp gauge picture illuminate. If i drive below 2500 rpm it doesn't matter what the traffic conditions are like the car doesn't overheat and the fan rarely comes on. Incidentally when it does over heat water comes shooting out of the header tank nowhere else.

paulbx · Post by **paulbx** » 26 Oct 2005, 13:38

With engine cold take off filler cap and rev engine - do big bubbles appear? If so seems like HG is cooked.
also feel the top hose - it shoudl ahve some give, if its rock solid with engine running and not so when off and cold also points to HG
The yellow warning light normally comes on when its critcal, theh red one normally means "too late!"
It could be a blocked radiator if the above tests prove negative or a stuck clsed thermostat.
However one overlooked item is the radiator sensor swtich which turns on teh fans this can be the cause of late or kalcg fan operation and costs about £10.
This is half way down the rad on l/h side and can be quickly replaced in 2 minutes - small loss of coolant.
I had a dodgy one and replaced it with another dodgy one! Eventually gave car away to enthusiasit who simply changed it again and hey presto fans came on at the right times!

Post by **Sir Clive** » 26 Oct 2005, 14:17

It sounds very like a clogged radiator to me as well. I used to have a BX turbo diesel, bought secondhand. I had to renew several hoses due to splitting, and thought no more of it until one day the dreaded yellow light came on......head cracked across all four combustion chambers....bugger.
The radiator, although looking fine exterenally had corroded and partially collapsed inside.
Although the head had cracked, the head gasket was fine, which was no real consolation!

citronut · Post by **citronut** » 26 Oct 2005, 19:14

i dont often see BXs with cloged up rads,unless someone has put far to much rad weld or dogy pelets,if the fan only cut in when your driving fast then it could still be air in thesystem or posibly fan sensor,i would still give it a thourgh bleed as i said earlier,you have got nothing to loose,always exhaust all other avenues before taking the head gasket route
rwegards malcolm

mak224751 · Post by **mak224751** » 26 Oct 2005, 21:52

Thanks all for the info.

How do i know if the head has cracked as I have not lost any power when i dare floor it.

Will do the checks to see if Head Gasket has gone is it easy to replace as i have only done a head gasket on a Mini 1000 before.

Interesting about the radiator as when it first started overheating i put some radweld in, as i couldn't see where the leak was coming from at first, to see if it solved the problem.

AndersDK · Post by **AndersDK** » 26 Oct 2005, 22:05

mak224751 wrote:The fan only comes on when the car overheats ie over 2500rpm and STOP light comes on and red lights by temp gauge picture illuminate. If i drive below 2500 rpm it doesn't matter what the traffic conditions are like the car doesn't overheat and the fan rarely comes on. Incidentally when it does over heat water comes shooting out of the header tank nowhere else.

I'm really sorry to inform you that this is a very firm symptom of a shot headgasket

To be sure :
From cold (

) engine - remove coolant filler cap. Then run engine at idle and slowly increase engine rpm by pulling the acc cable. If air is now violently bubbling up the filler neck - even expelling the water - you have the most sure indication.

My first car was also a Mini - and me too I did the HG on this

Last year we did the HG on son-in-law's (non-turbo) diesel BX. Much the same type of work.
* BUT * - you have the turbo which does complicate things a bit. Main thing is to avoid trying remove the turbo from head while on engine. Remove head with manifolds and turbo as a unit. May sound buzz - but it is in fact the easiest method.
* ALWAYS * have the head milled (skimmed) when removed - or the complete job is waste of time

citronut · Post by **citronut** » 26 Oct 2005, 22:47

if all fails when you have made 100% sure there is no air in the system and you still have the prob,add to anders reply have the valves sunk into the head to the corect depth otherwise the will allmost certainly contact the pistons
regards malcolm

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