Step-by-step process to check overheating

First off - I've searched thru the forums and read up on the usual suspects for an overheating 300tdi: head gasket/warped head, stat, airlock, blocked pipes/rad, water pump etc. And while I'm not a great mech, I guess the solution maybe to give the Defender (90, R-reg, 96k) to someone who is and pay them to do this. However - out of my own curiosity....

What checks should I do first that don't require much mech know-how? Jetwash the rad? Run it for X-mins at Y-temp with the expansion tank cap off and sniff for fumes?

Can't see any white smoke out the exhaust; the timing belt looks slightly worn and the top pulley seems very shiny - so loose belt? There is a ch-ch-ch-ch-ch noise (not squealing budgies) occaisionaly from up the front - so water pump/belt issue?

And how to check for airlocks?

Essentially, I'm one of those guys that doesn't mind giving it a go, but I always find, if I have 4 bolts to undo, I can do 3, but the 4th one refuses to budge And with just the one car to get me to work, I can't really have it off the road for a few weekends while I tinker.

Cheers, Matt

does it only overheat when you are moving, like the motorway, mine was fine on idle and round town, but on the motorway the temprature went through the roof!
ch ch ch ch noise is exactly what i had, its a warped head... I had it skimmed 10thou off (.25mm) re-ground the valves, stem seals, fitted a new timing belt and tensioner, idler and crank pulley etc also a new water pump and thermostat (just for peice of mind)

Where abouts are u based? Its a dead easy job to change it all..

discobiscuits said:

does it only overheat when you are moving, like the motorway, mine was fine on idle and round town, but on the motorway the temprature went through the roof!

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can drive it for about 5miles and needle's dead centre. Then it starts to move. Fine on idle. Haven't taken it on motorway for just that fear...

discobiscuits said:

ch ch ch ch noise is exactly what i had, its a warped head... I had it skimmed 10thou off (.25mm) re-ground the valves, stem seals, fitted a new timing belt and tensioner, idler and crank pulley etc also a new water pump and thermostat (just for peice of mind)

Where abouts are u based? Its a dead easy job to change it all..

Click to expand...

You're taking the mick? Doesn't always make that noise - hasn't recently, I don't think. But haven't noticed if it does it when it's really hot - which I haven't done for a few weeks since this started etc etc.

I'm north Cheshire - M56/M6 area. Any ideas?

Sounds exactly like my Disco .. which we traced to a broken radiator. At least half the fins were blown out the back and couldn't be seen without lifting the rad. Dunno if the Defender's the same, but the Disco rad also has the oil cooler incorporated and we reckon it was this that really gave us problems.

I also had a ch-ch-ch noise that was traced to the exhaust manifold stud closest to the bulkhead found to be missing and exhaust gasket blown through!

Paul D said:

which we traced to a broken radiator. At least half the fins were blown out the back and couldn't be seen without lifting the rad. Dunno if the Defender's the same, but the Disco rad also has the oil cooler incorporated and we reckon it was this that really gave us problems.

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Hmm - good point. Had a look and there it does seem to be a bit lacking in all the fins. In some places there are just the horizontal bars... I guess with a couple of driving lights on an A-frame in front means less air getting in anyway...

Paul D said:

I also had a ch-ch-ch noise that was traced to the exhaust manifold stud closest to the bulkhead found to be missing and exhaust gasket blown through!

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It comes and goes - almost think it might be related to getting water from driving through water up under there.

My other thought was the thermostat - since the temp seems fine for a bit, then takes off at about the time you'd think it was up to temp. Fine - if the stat is working properly, and it _is_ the rad. Alternatively, the fact it's constant temp, then increases might suggest the stat is in fact OK - ie there is a point where something "switches"?

Anyone any views on the product advertised in a "sponsored link" at the bottom of this thread??!

Steel Seal- Head Gasket Repair

Gut instinct is: quick fix that will cost more in long run if gums up engine...
Alternatively: quick/simple test to see if it is head gasket problem if it works...

Matty said:

Anyone any views on the product advertised in a "sponsored link" at the bottom of this thread??!

Steel Seal- Head Gasket Repair

Gut instinct is: quick fix that will cost more in long run if gums up engine...
Alternatively: quick/simple test to see if it is head gasket problem if it works...

Click to expand...

update?

Do not use a HG repair liquid, you're only delaying the inevitable

Matty said:

the timing belt looks slightly worn and the top pulley seems very shiny - so loose belt?

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If you can see the belt and pulley and haven't stripped anything off the engine then that will be the serpentine belt you are looking at and not the timing belt.

Matty said:

Hmm - good point. Had a look and there it does seem to be a bit lacking in all the fins. In some places there are just the horizontal bars...

Click to expand...

Sounds like you need radiator anyway (or will soon). Bite the bullet and replace it (also flush the system through to clean the crud out). It may cure your issue