The techies on BX Club are number 1!

BX Tech talk
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Kitch
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The techies on BX Club are number 1!

Post by Kitch » Wed Dec 27, 2006 6:27 pm

I know no forum with a more helpful, quicker acting bunch of blokes than this one.

So now a test....can you apply your knowledge to a car that isn't a BX? :!:

The car is my newly purchased Rover 216i. The problem....cooling system! Now before anyone just says "head gasket", please read on.

On several occasions now, I've come back to my car having parked it up after a run to find a big puddle of coolant on the O/S/F of the car. At first I assumed it was a flange or a leaky water pump, as its roughly under the timing belt area, but not quite.

However its not a constant leak. It only ever seems to do it once the car has been for a run, and then left to cool. But not everytime either, as I parked it up at work this morning, came back 6hrs later and it was bone dry underneath.
Having just jacked it up and run it hot, I can find no leak at all! :shock:
Its bone dry under the car, no real traces of a leak anywhere under the bonnet! With the engine on or off, there was no leaking anywhere.

The only odd thing that did happen, is that I left the cap off the expansion tank while it was running, as I tried the bleed screws to check for any air in the system.....couldn't find any. On this car, there is a small pipe which comes off the top hose and returns to the top of the expansion tank via the head. When you rev the engine, this returns water to the tank, the more being returned varying on the speed of the engine.
While the engine was getting hotter, the level in the coolant tank was slowly rising. I'm told this is normal in these cars, as this return pipe can fill them quicker than they drain. However when the cooling fan cut it, it all pissed out the top like an erupting volcano! In the BX, the level rises and then suddenly drops the second the fan cuts in, so you can imagine I was surprised!
It behaves as good as gold in any other way. With the lid off, and the engine revving there is no bubbling or anything in the tank. The coolant is clean as a whistle, no white gunk in the oil either. It doesn't seem to overheat, and the needle never exceeds the normal position for one of these cars.

My theory was that I'm getting a puddle, because the car is parked up hot, then slowly cools down. The water escapes from the tank as it does, just like when the fan cuts in. I know the cap doesn't hold the water back either, so I was wondering if the coolant is dribbling out, running down the bulkhead somewhere and exiting on the OSF, as the coolant bottle is on the NSF! But again, this theory doesn't hold water (no pun intended) as the car was parked leaning to the left on my gf's driveway.

But why would it burst out like this when the car is being cooled down? I can't work out if I'm leading myself up the wrong path or not here.

So basically..........eh?! :?

We need the car to go anyway to Devon for our anniversary on the weekend. :( Any help greatly appreciated. If you solve the mystery, my 16v is yours for a 30minute countryside blat :lol:

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cavmad
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Post by cavmad » Wed Dec 27, 2006 6:43 pm

Getting slightly hotter than it should and lobbing coolant out of the breather pipe when it cools?
Have you taken it to a garage for a pressure test to see what it shows up?
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Post by Kitch » Wed Dec 27, 2006 6:53 pm

It doesn't actually get hotter than it should, it just behaves weirdly when its starting to cool down after being warm.

Not had a chance to get to a garage...most aren't open til next week and the ones who are, are fully booked. I guess you need some sort of special tool to do a pressure test?

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Post by Vanny » Wed Dec 27, 2006 7:18 pm

This should be in general chat!!!!


Whats the radiator like? Is it consistent temperature all over?

Im thinking something along the lines of its heating up and blocking a pipe building pressure up behind it, cools down, opens pisses pressure out?

Either that or a cracked block leaking pressure? Could of course be getting HOTTER when you turn the engine off, it wont be cooling downt he instant the car has stopped!

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Post by Kitch » Wed Dec 27, 2006 7:22 pm

Why should it be in general.....its a technical question :P

Rad seems fairly equally placed in terms of heat. I don't think its leaking straight after its been switched off either, I think it happens a little while after, but having never witnessed it leaking I couldn't say :lol:

Could be a cracked bloke, that though did cross my mind. But surely there would be marks on the engine? Or a small trail down underneath the crack? Because the engine is clean as a whistle!

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Post by tom » Wed Dec 27, 2006 8:37 pm

Is the car cooling down? Maybe the fan wiring is reversed.
.001% chance of that though. When the fan cools the water, the thermostat is obliged to shut and the circulation goes askew. As it cannot come out of the top, it boils up in the block and comes out through the bottom, emerging at the header tank.
That is a plausible explanation for what is happening. What motor is this one Kitch? is a 216 a Rhonda or one of those Leyland atrocities?
I reckon that it is an air lock though and that obserbing behaviour on a good sized header tank will either allay your paranoia or upset you.
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Last edited by tom on Wed Dec 27, 2006 8:38 pm, edited 1 time in total.
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Post by roscoe » Wed Dec 27, 2006 8:38 pm

Cuuld well be a hose with a pinhole in it that is leaking under pressure. When you shut the car off from hot, the coolant temperature in the block increases as it is not circulating anylonger. The pressure builds up and any tiny holes in a hose will then spew coolant until the pressure goes back down as the engine cools. Same thing could apply to a cracked block/head/thermostat housing, etc. I had a car (non Citroen) do this to me years ago and it took a long time to find - a normal pressure test didn't find it - finally made my own testing rig from an old rad cap and tire inflating valve soldered into it - connected up my air compressor and gauge and at 40 psi (3 bar), the hose started spewing coolant out of a very small hole.
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Post by tom » Wed Dec 27, 2006 8:41 pm

I would NOT trust a modern radiator at three bar. Although it is a valid test, you shouldn't either!
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Post by Kitch » Wed Dec 27, 2006 8:59 pm

Thanks for your help so far, I have to admit an air lock did spring to mind, but as I can only find one bleed point and didn't see any air there, I dismissed it. Maybe I should give it more time?

Its the Rover K Series lump, the one that blows head gaskets for fun :lol:

I'll have another go at bleeding it tomorrow. :)

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Post by Kitch » Wed Dec 27, 2006 9:05 pm

Course the other problem I just thought of, is why is it leaking on the OSF of the car, when the expansion tank is on the NS? I can't see anywhere for it to run to.

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Post by tom » Wed Dec 27, 2006 9:13 pm

Oh. I feared as much. Discontinue hostilities until you find out how to bleed it properly because they are notoriously counter intuitive and if you get it wrong, the head gasket will pack up.
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Post by Stinkwheel » Wed Dec 27, 2006 9:27 pm

Actually our old 1.4 K series 400 did this a couple of times. Never did figure it out though. The reason for the headgaskes failing on these has been explained to me as the waterways being too small on these engines and if any part of the cooling system is a little less that ideal it all goes a bit wrong, i've no idea if this is actually the case though.
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Post by cavmad » Wed Dec 27, 2006 10:32 pm

I had a Honda engined 416 (least I think it was a 416) anyhow that was misbehaving and had cracked the head which I was told was a common problem. Sorry if you didn`t want to hear that mate and I certainly hope that`s not the case with your`s.
Sleepy used to be a Rover mechanic at a franchised dealer iirc, perhaps he`ll know when he gets back on here?
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Post by Vanny » Wed Dec 27, 2006 10:40 pm

Kitch wrote:Why should it be in general.....its a technical question :P

BX Technical, that and Rovers are evil with far to many 'quirks' to be considered anything but a general car.

I like Roscoes explanation best, but as it seems you already know, these engines are notoriously weak! The block could be cracked internally ie leaking cylinder pressure into a water way like mine. Guess you would need a compression test to know that.

Whats the fluid actually like? Is it clean? Might be worth flushing it all out and refilling with correct bleeding, cheaper than any other option!

And if its all coming from the oposite side from the header tank then i guess that means something is is leaking/bleeding out the pressure. Hasn't got a secondary bleed on the radiator or something daft has it?

tim leech

Post by tim leech » Wed Dec 27, 2006 10:48 pm

Could be the system pressuring and the water blowing back past the expansion tank? have heard of that before.