what causes over heating in the cylinder head

[damongrounsell]

So my head looks like its cracked. 1.6td jx, not rare, but what actually causes the over heating issues and how can you fix the over heating before the damage is done. Its a local issue rather than a coolent based problam isn't it.
is is fuel mixture, timming, turbo settings?
please you technical fiends enlighten my enquiring mind

[dave friday]

a bit more info please,like where are the cracks,and history?...is the engine in bits?.

[peasant]

Proper timing, turbo boost, injection and valve clearances all play a role and I'm sure proper experts (i.e. not me ) will be along to elaborate ...but the single most important factor is how you drive it.

While the turbo diesel offers 38% more power that the normally aspirated engine from pretty much the same basis, it is decidedly unwise to try and convert this into 38% more speed ...especially so over long periods.

The long distance cruising speed of the jx still is only 100 km/h or thereabouts, pedal to the metal motorway journeys will cook your engine in no time at all.
The same goes for hill climbing or trailer towing, as soon as you demand 100% power for prolonged periods your goose is cooked.

Drive it with sympathy, keep an eye on the temp, allow it to cool down before switching off.

[Wolfsburg Willy]

I agree with you on this one Peasant. Technology has come a long way in the twenty or so years that our vans have existed and engine design is far better understood nowadays. Some engines designed in the 80's had inherent faults such as cylinder head hot-spots or cooling system weaknesses that meant that they would sooner or later, under certain conditions, fail. Bearing in mind that it can take up to five years between conception and the mass production of an engine, the JX engine design could be older than we think! It would be too much for any Engine Design Team to consider what the consequence of excessive carbon deposits or worn valve seats would be in twenty years time. We do not as a routine maintenance item remove, decoke and inspect cylinder heads at, say, 150,000 miles/15 years 'cos (a) "if it ain't broke - don't fix it!" and (b) Mr. Volkswagen didn't say that there was any requirement to do so. So the answer to your question Damon is yes, all those things! As Peasant says "Proper timing, turbo boost, injection and valve clearances" plus head decoke including injectors, using the correct coolant, correct head tightening if the head's been off etc. etc. etc. Do any of us know the full history of our engines if we haven't owned them from new (or rebuilt them)? Don't worry about it, just fit another head and get on with enjoying your van!!

[camper]

I agree with you on this one Peasant. Technology has come a long way in the twenty or so years that our vans have existed and engine design is far better understood nowadays. Some engines designed in the 80's had inherent faults such as cylinder head hot-spots or cooling system weaknesses that meant that they would sooner or later, under certain conditions, fail. Bearing in mind that it can take up to five years between conception and the mass production of an engine, the JX engine design could be older than we think! It would be too much for any Engine Design Team to consider what the consequence of excessive carbon deposits or worn valve seats would be in twenty years time. We do not as a routine maintenance item remove, decoke and inspect cylinder heads at, say, 150,000 miles/15 years 'cos (a) "if it ain't broke - don't fix it!" and (b) Mr. Volkswagen didn't say that there was any requirement to do so. So the answer to your question Damon is yes, all those things! As Peasant says "Proper timing, turbo boost, injection and valve clearances" plus head decoke including injectors, using the correct coolant, correct head tightening if the head's been off etc. etc. etc. Do any of us know the full history of our engines if we haven't owned them from new (or rebuilt them)? Don't worry about it, just fit another head and get on with enjoying your van!!

Hey ho sounds very technical. Here is my explanation a lump of silicon gasket sealent used in the coolent system for thermostat housing /coolent pump& other flanges. Seriously this happened when some of this silicon sealent was curculating and blocked up a coolent hole in the cylinder head.The effect caused overheating on the head.

[lloyd]

Agree with above.

Keep in mind these engines were designed for small light cars, not big heavy vans. They last forever (almost) in cars, but many overwork (thus overheat) them in vans trying to hold speed on hills or motorway. Never run at full throttle for more then a few minutes and always slow down a few miles before stopping so they can cool down some. Also let them idle for a few minutes after running at speed or working to cool down the turbo and head.