Problems after new radiator fitted {high temp then shut off}

r4y007 · Post by **r4y007** » Sun May 27, 2007 4:21 pm

Hello,

I had a radiator leak and was told had to have the whole thing replaced, so went to a small garage who did the job but I think not properly! Since then had a problem of my car shutting down when temp goes around the 90 mark, I have noticed that it goes a few mils above then shortly after car just cuts power! If I wait about 15 minutes it re-starts (cools down I guess)

I've been advised that either the radiator needs 'bleeding' as could have airblocks or that the fan is not kicking in or working properly.

Does this seem normal and any hints?

Thanks

niz406 · Post by **niz406** » Sun May 27, 2007 8:36 pm

Hi Chap,

What Car are we talking?

V6Exec · Post by **V6Exec** » Mon May 28, 2007 10:19 am

Airlocks :-(

I had a ZX. Great design flaw in the cooling system. The temp probe gets airlocked and reads fine. Meanwhile the engine overheats, the sump gets sucked though the combustion chamber (making it a real oil burner :-) ) and the content of the radiator gets vapourised.

I did learn something that day - check the bleeds on the cooling system. You need a header tank and the best one I have found is a 2 or 4 pint milk container. The top fits perfectly and you can give it a squeeze to speed the process :-)

r4y007 · Post by **r4y007** » Mon May 28, 2007 4:32 pm

Thanks for the reply.

The car is a 406 TD (90 bhp) 1999 (T) unfortunately I don't know much about the mechanics of cars (apart from where the fuel, water & oil goes) I've got it booked into a garage next friday but at least I have a very good idea what it is. At high speeds on the motorway etc it is ok the temp seems relatively low around 70 I think but during traffic it slowly rises (I think at a normal rate) to the 90 mark then a few mils over which I'm very sure it didn't do before then shortly after the car just turns off and won't re-start, I usually push it aside or roll aside if I can then open the bonnet and wait for about 5 minutes before re-starting it, then it starts fine and the temp is low again.

So I should fit an empty milk bottle to the hole where the coolant goes then squeeze it? I assume this will force the water/coolant to force its way to any airlocks?

Cheers

V6Exec · Post by **V6Exec** » Mon May 28, 2007 5:07 pm

With the milk bottle the trick is to make sure it is clean first - obvious but easily overlooked. Next fill it with coolant mix, take off the coolant filler and swiftly invert the bottle and jam it down te hole. Keep pressing and you get a good seal.

Next go for the bleed caps. These are a bit like the dust caps on the tyres, there is one on the hose going to the passenger compartment and another on the way to the radiator. They may be more, but once you spot them they are easy to recognise. Remove each one in turn and give the bottle a light squeeze until liquid comes out the bleed valve. Put the cap back on and do the next.

Haynes manual suggested cutting the bottom off a coolant bottle and using it that. Milk bottle is simply bigger.

Once bled if you still have the problem it was not an airlock.

mjb · Post by **mjb** » Mon May 28, 2007 8:07 pm

It's easier to just park the car with the drivers side raised - a small kerb will be enough - and fill the expansion tank to the top. Leave the cap off while you're bleeding it otherwise nothing will happen.

As I said in the other thread though - don't do this first. It may prevent being able to troubleshoot what's causing the engine to stop. If your fans are broken and you have an airlock, removing the airlock will only hide the problem of your fans not working, which could cause some nasty consequences if one day if the car really needs that fan!

Let the engine idle for a bit until the temperature reaches over 90. Have the bonnet open and watch/listen for the fans. If the engine cuts out with no activity from the fans, you've found your problem and will need to check if they're actually plugged in or something silly.

niz406 · Post by **niz406** » Mon May 28, 2007 8:24 pm

Could also be too much system pressure causing the cut out.... ?!

r4y007 · Post by **r4y007** » Mon May 28, 2007 11:35 pm

I will check whether the fan is coming on as this seems the easiest thing todo first, hope its one of these things as already taken to a garage who fiddled with the turbo and charge me for nothing just gettin fed up with garages 'having a guess' and not solving anything apart from how to fill in a invoice!

I'm just concerned if either of these problems would cause the engine to shut off? (fan not kicking in or airlocks in radiator)

Too much system pressure, sounds expensive to repair!

niz406 · Post by **niz406** » Tue May 29, 2007 12:48 am

Not really.... too much system pressure could just be a small leak somewhere... when the engine is running, can you squeeze the waterpipe from the radiator?

mjb · Post by **mjb** » Tue May 29, 2007 12:52 am

r4y007 wrote:I'm just concerned if either of these problems would cause the engine to shut off? (fan not kicking in or airlocks in radiator)

Well my thinking is it may be a mix of an airlock in the cooling system causing the temperature to get high (for a diesel) and then the ECU deciding since it's getting hot and it can't switch the fan on to cool down, it should probably kill the engine to prevent catastrophic damage... It's a logical path, but whether or not it's what's actually happening you'll have to find out.

jameslxdt · Post by **jameslxdt** » Tue May 29, 2007 7:31 pm

mjb wrote: Well my thinking is it may be a mix of an airlock in the cooling system causing the temperature to get high (for a diesel) and then the ECU deciding since it's getting hot and it can't switch the fan on to cool down, it should probably kill the engine to prevent catastrophic damage... It's a logical path, but whether or not it's what's actually happening you'll have to find out.

the ecu is so stupid on the 1.9 td, it cant actually switch then engine off

mjb · Post by **mjb** » Tue May 29, 2007 9:52 pm

jameslxdt wrote:the ecu is so stupid on the 1.9 td, it cant actually switch then engine off

erk! maybe something crazy like shorting fans that someone's fused with an old nail? That'd kill power to the fuel pump...

r4y007 · Post by **r4y007** » Tue May 29, 2007 10:07 pm

Hey guys,

I checked the car after a short drive to see if I could see the fan, I think I could but it definately wasn't moving at all, although I don't know if thats normal? The car wasn't hot anyway but does it normally spin very slightly or not at all until the temp is high?

Next chance I get when the temp is around 90 I'm gonna definately check it to see if it comes on or not.

philmeboots · Post by **philmeboots** » Wed May 30, 2007 11:37 am

sounds like you've got a similar mind warping problem to my 2.0 petrol - I first eliminated the fan by removing the front grill and first checking all the wiring, resistors and relays - then the actual fan by measuring the resistance of the motor. All this was fine so I've assumed its the coolant temp sensor.

However, after reading this, I'm now thinking it could be an airlock or something similar!

Can anyone tell me if I should be able to see the coolant pumping around if I take the cap off the expansion tank? (I cant see anything moving but it also looks slightly overfilled

!)

The other question bugging me is that when the car is warm/hot, I feel the pipes around the Rad and the bottom pipe feels cold as if there's a blockage - could this possibly be the thermostat?

Basically I've had the same problem where my car just randomly shuts the engine off (not overheated), and I've also got the overheating problem when I sit in traffic ("Temp too high warning" on display) - Its a 406 99/v 2.0 16v.

mjb · Post by **mjb** » Wed May 30, 2007 12:42 pm

philmeboots wrote:Can anyone tell me if I should be able to see the coolant pumping around if I take the cap off the expansion tank? (I cant see anything moving but it also looks slightly overfilled !)

DO NOT DO THIS WHEN THE ENGINE IS HOT!!! The coolant system becomes quite pressurised and you really don't want scalding coolant shooting up at you, not to mention the steam will be toxic... Trust me on this...

The expansion tank cap is actually a pressure valve which will vent is the pressure gets too high, so basically there's no real risk from over-filling (unless your face is anywhere near the cap when it vents...

). I really wouldn't expect much visual indication that the cooling systems working apart from heat haze over the radiator. Just find your bleed nipples when the engine's cold (Haynes should tell you), take the expansion tank cap off, and undo the bleed nipples until liquid comes out.