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300tdi serious overheating

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Hi All, Please could someone guide me before I invest in 5lt of petrol and a box of matches.

300tdi engine keeps on over heating, but in a strange way. While driving noticed the temp gauge getting too high and changed water pump and thermostat. But what happens is after putting in water and anti freeze and bleeding the system, when you start the water in just a short time 2 min. is forced passed the pressure cap, which is new also and replaced at least twice since. Resulting in almost no water and overheating.

Explanation of what I have done so far:

Took it to a radiator specialist they tested for leak from the head. nothing just pressure. This exact problem started about 50-000km ago. Have taken it into reputable Land Rover workshop, they did a complete overhaul. Not even 1500km down the road same thing started again. This time new head and gasket. same thing. Then did a new head gasket myself, this lasted about 10-000km and same again. Again took it to Land Rover specialist they put a new head and gasket, water pump, thermostat, radiator cleaned and service by rad specialist.

I have since striped the engine completely. Head went to specialist and skimmed, block skimmed. All new bearings, rings, oil pump and plate and gaskets, new water pump and thermostat. Every part put back according to manual step for step everything torqued.

Drove about 35km nice a slow for first drive since the rebuild and noticed that temp normal but oil pressure dropped from 3 bar to about 1.2 bar. Stopped and the thing was over heated and boiling. After putting in more water and started the engine water was again forced out passed the pressure cap?

Who can help?

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Could be worth checking the bypass hose from the thermostat housing and top of radiator to the expansion tank isn't blocked. The three way union is known to collect debris and choke the flow.

This hose bleeds off air from the highest points on the head (thermostat housing) and the radiator. If blocked, air collects in the head/rad and the engine overheats rapidly. Although the symptoms sound severe, it's got to be worth a (free) look before committing to a failed engine.

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Thanks for that guys,

yes the three way pipes have been checked out and on one of the many re-filling of water I discovered a block. got that sorted. and the other hoses have also been checked out as well. The heater is not connected at all.

What's got me baffeled is when had the head and block were skimmed. I sent both to be pressure tested. And apparently all is well.

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i have to agree sounds like exhaust gases getting into your coolant which sound like either a cracked block or warped head

but i have had many many an overheating problems with my 300tdi almost everything has been replaced, i also found the small bore bleed pipes to be blocked but on one occasion i also ran with no heater.

so heres some suggestions

i know it sounds stupid but have you plumbed straight through where the heater should go??

i found when i did this my overheating was worse as the coolant flow wasnt right, id suggest reinstalling heater and also check it out for good flow before re-fitting

also check for any small leaks in the system, if your loosing any pressure then the coolant will boil at a lower temperate, so pipe joints and water jacket plugs are a good part to check

if still over heating try removing your thermostat for a bit or get a lower temperature rated one

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i found when i did this my overheating was worse as the coolant flow wasnt right, id suggest reinstalling heater and also check it out for good flow before re-fitting

IIRC The heater matrix has a constant flow going around it, it is always "on" so it would act like a radiator... the normal over-heating "get me home" solution is to whack the heater on full, so it would suggest not having it on the system at all would cause you grief!

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