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elbekko

Overheating after top end rebuild

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Yup, that's described in the RAVE, and my setup is already the higher pipe.

7 minutes ago, David Sparkes said:

My experience is more diesel than petrol, so I didn't think I could usefully contribute, but having now seen the diagram ...

I'm pretty sure there was a Tech Bulletin about this, it concerns the thin green radiator bleed hose (16). After draining, if coolant remains in the lowest section, with air in the higher sections at either end, the pipe is too small a bore to self bleed. An air lock then develops in the top of the radiator, inhibiting flow.

The expansion tank will get hot, via the purple expansion pipe (20), but there will still be no flow.

The in service work round was to remove the cap from the expansion tank, remove the bleed hose from the radiator, then blow (lung power only) along the pipe towards the expansion tank. When you heard air issuing from the tank you knew the pipe was clear.

The factory cure was to reroute the pipe along the top of the inner wing instead of dropping down to the 'chassis rail', thus eliminating the giant U bend.

Regards.

 

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5 minutes ago, elbekko said:

Yup, that's described in the RAVE, and my setup is already the higher pipe.

Oh well, at least I passed the memory test.
As you are grasping at straws, I assume the pipe has been proven clear anyway?

Regards.

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32 minutes ago, David Sparkes said:

Oh well, at least I passed the memory test.
As you are grasping at straws, I assume the pipe has been proven clear anyway?

Regards.

Yes, blown through both manually and with the compressor.

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41 minutes ago, P38 Paul said:

Is the top hose hot all the way down to the thermostat ? if so , & the bottom hose is cold the only thing in the way is the thermostat .

If the top hose is cold at the thermostat it could be blocked or collapsed inside therefore restricting the flow , good luck , I feel your pain .

 

That's one of the things I need to double check. But since the water pump suction hose is warmish, I would assume so. The annoying thing is that the bypass hose is hard to reach to feel/measure, even with the wheel well liner gone.

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I second that, we need to try and determine how far each hose gets hot. Your diagram will make things easier.

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Yup. I hope Escape can have a look today during the day, and I'll be taking another look at it tonight (have to work, sadly). Hopefully we find something.

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probably just going with the flow ........:ph34r:

Sorry couldn't resist , I've been following this and it is a puzzle , my thoughts were as others have already suggested - drive belt route , pipe connections but you have covered it all . An IR temp. reading of various spots might show something , I hope you are successful .

cheers

Steve b

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2 hours ago, Escape said:

No pun intended, I'm sure. 😉

No, it wasn't, but then this close to christmas, who knows what is going through my brain!

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Well... she's fixed :D

Many thanks to @Escape, he'd done what I was planning on doing by the time I got there - disconnected the bypass hose, put it into a bucket, and started the engine. Took a little bit for the flow to start, but then it started flowing properly (do correct me if I'm wrong here!). Connected everything back up, let it idle for 15 minutes, and no overheating.

I then took it for a drive, about 40km, on small roads, motorway (at legal speeds officer, I swear), and a bit of off-road. Temp stayed perfect. I had the Lynx hooked up the whole time, at the start it was around 100°C, a few km later she stayed around 90°C. Saw the thermostat working nicely.

So after all, it must've been a massive air pocket in the block that couldn't get out in time through the little vent lines.

Thanks for thinking along everyone, and I'm very glad she's back to life :D

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Glad to hear it was something cheap and simple.  300Tdis get a similar problem with their vents lines from rad top and thermostat housing to the tank, usually because the Y-piece blocks up.

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Marvellous, well done persevering :)

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37 minutes ago, miketomcat said:

Just in time for the 30th see you at bunny lane then. :stirthepot:

Mike

Yup! So glad we got her fixed in time for the trip.

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Just booked the ferry, we'll be there! 😎

Just to add, we did take a lot of readings with the IR-gun, but it's not always that accurate. Especially on hoses, at best you can get an idea of heat distribution. But not something I would trust to say the temperature is OK. As Ben said, I put the bypass hose in a jug and got a good flow pretty quickly. I could hardly keep up filling the expansion tank. I reconnected everything and let her idle with the cap off. Temperature stayed stable just under half on the gauge. Temperature as recorded by the ECU did rise, but at first the heater cooled didn't get very warm. Then the level in the tank started rising so I replaced the cap. This was probably the thermostat opening. A bit later the gauge made a brief swing towards red, but immediately came back, so it looks like a big air bubble needed to pass. After 5 more minutes at idle with the temperature perfect, I had to run off to go and help with the christmas dinner but I was confident enough to let Ben jump in and go on a testdrive. Which apparently resulted in a big grin. 😁       

Thanks for all the suggestions guys!

Filip

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