637Nook

Cheers Muddy that makes a lot of sense, never thought of that! back to the garage to pull the head off again then.... if its cracked are we liable to be able to physically see it? Cheers for the advice appreciate there's a lot of experience on here

Cheers guys, I'll try and find someone that can pressure test it.... we did the head gasket ourselves as were both pretty good with the spanners, just replaced the gasket, head looked fine and went back on and ran fine for the 9months so far until this problem

Hi Guys, I wonder if any of you techies out there has any ideas, my brother has a 300tdi its run fine for the past three years apart from blowing the head gasket about 9months ago which was replaced without incident and has been running fine since. Now to the problem, about 6 weeks ago the belt tensioner on the front of the engine some how loosened itself and came off, this in turn shredded the fan/alternator/water pump belt I managed to get the 90 home without the temp gauge getting anywhere near the red, the tensioner was refitted and a new belt added everything ran fine........or so we thought..... short hops below 40mph the engine temp stays low, as soon as you do a longer/faster journey the temperature gauge goes up into the red, the internal heaters blow cold while the temp gauge keeps rising....they will then suddenly blow hot and the temp gauge will drop down to normal running temp, after a very short time the blowers go cold and the temp starts going up again!.... My first thought was thermostat, this was replaced with a new one (checked and working before installation), no change.... Water pump checked, replaced with a new one, no change..... Expansion cap replaced (in case the system was not self releasing air properly) no change...... All the hoses removed and water blasted through the system by hose to remove/check for blockages, no change..... We are now running out of ideas and the problem remains.... !!? Anyone out there got any ideas or suffered anything serious? the only other thought we have had is that the head gasket has gone again and is over heating/pressuring the system but I thought before we pull the head off i'd ask if anyone has any ideas!? Cheers Guys Andy