Orange Posted November 26, 2009 Share Posted November 26, 2009 I'm scratching my head!! My 300 has been suffering from overheating. I've replaced the viscous unit and that worked wonders, but not perfect. I replaced the rad and it now runs as cool as a cucumber... Took it for it's MoT on Saturday (about 50 miles) and temp never raised above 1/3 on the guage. However, after 2 days of sitting, I opened the header tank to check the water level and it erupted up my arm. Is there anything wrong here, or am I making a mountain out of a molehill?? I'm currently replacing a snapped timing belt (done on the way home from the MoT!!!) and will be taking the head off to check all the pushrods etc, so would like to get it all sorted at the same time if anyone can offer any bits to check or replace while I'm doing it... I'm thinking that I'll replace the thermostat anyway, just to rule it out... TIA Adrian Quote Link to comment Share on other sites More sharing options...
markyboy Posted November 26, 2009 Share Posted November 26, 2009 I'm scratching my head!! My 300 has been suffering from overheating. I've replaced the viscous unit and that worked wonders, but not perfect. I replaced the rad and it now runs as cool as a cucumber... Took it for it's MoT on Saturday (about 50 miles) and temp never raised above 1/3 on the guage. However, after 2 days of sitting, I opened the header tank to check the water level and it erupted up my arm. Is there anything wrong here, or am I making a mountain out of a molehill?? I'm currently replacing a snapped timing belt (done on the way home from the MoT!!!) and will be taking the head off to check all the pushrods etc, so would like to get it all sorted at the same time if anyone can offer any bits to check or replace while I'm doing it... I'm thinking that I'll replace the thermostat anyway, just to rule it out... TIA Adrian Air locked due to the overheating problems you've experienced? Was the heater warm? If the stat was faulty I'd expect it to overheat, unless it's stuck open, but that wouldn't cause the system to pressurise per se. Incidentally, only 1/3 on the gauge seems low. Also, I don't think it's absolutely necessary to remove the head to check/replace the push rods. Removing the rockers should allow you to extract the push rods to check for bending. Hopefully an adult will be along soon to confirm/deny what I've said. Mark. Quote Link to comment Share on other sites More sharing options...
Orange Posted November 26, 2009 Author Share Posted November 26, 2009 Cheers Mark. The head is coming off because I want to make sure there aren't any issues after the few times it has overheated... There don't appear to be any, but while I'm taking it all apart, I might as well!! The heater has been warm throughout all the issues, so I don't think it's airlocked, sometines it's been HOT, but that's the overheating. I make a point of making sure the car is facing 'up' the drive when it's refilled so the heater isn't the highest point! ............. Quote Link to comment Share on other sites More sharing options...
markyboy Posted November 26, 2009 Share Posted November 26, 2009 Cheers Mark. The head is coming off because I want to make sure there aren't any issues after the few times it has overheated... There don't appear to be any, but while I'm taking it all apart, I might as well!! The heater has been warm throughout all the issues, so I don't think it's airlocked, sometines it's been HOT, but that's the overheating. I make a point of making sure the car is facing 'up' the drive when it's refilled so the heater isn't the highest point! ............. Only other thing I can think of then is head gasket failure between combustion chamber and water galleries pressurising the system. Would normally recommend a "sniffer" test but if you're having the head off then it should be evident. Mark. Quote Link to comment Share on other sites More sharing options...
rocky Posted November 26, 2009 Share Posted November 26, 2009 Hi, mine blew the gasket between no. 3 and 4 cylinders. It overpressured that much it blew the bung out of the thermostat housing. The top hose was always solid. But I also lost the heater. Hopefully yours is alright, but it does sound like a headgasket. If you do remove the head it would be a good idea to get it pressure checked and possibly skimmed. Regards, rocky Quote Link to comment Share on other sites More sharing options...
Tetsu0san Posted November 26, 2009 Share Posted November 26, 2009 It seems to be the time of year when 300Tdi engines have problems. There seem to be quite a few threads on this forum pointing to head problems. I have just done the head gasket and replaced the head on mine and I had very similar issues to what you are experiencing. Mine blew a hole in a core plug at the rear of the block, which was a nightmare to fix. I would second what Rocky has said and advise you to get the head pressure checked at least and then get it skimmed if that passes. And don't be tempted to get a metal head gasket, get an Elring gasket instead. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted November 26, 2009 Share Posted November 26, 2009 My disco V8 was doing exactly that, and it was caused by me not removing the plug in the top of the rad when filling it with water. Had a huge airlock. Quote Link to comment Share on other sites More sharing options...
Orange Posted November 26, 2009 Author Share Posted November 26, 2009 OK, so it sounds like I'm heading down the right track... Have had the timing chest off tonight and it's like oily porridge (best way I can describe it) splattered all over the place, so this points more at over pressurisation of the entire engine rather than just the water system! More investigation, methinks!! Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted November 26, 2009 Share Posted November 26, 2009 Perhaps blowing to an oil-way or push-rod hole as well as a water-way? I'm sure all will be revealed when the head comes off Quote Link to comment Share on other sites More sharing options...
Orange Posted December 20, 2009 Author Share Posted December 20, 2009 To bring a close to this... The head was removed and there was no evidence of a 'blow' on any of the surfaces or the gasket. Took it to be pressure tested and all was good. The machinists did suggest skimming it by 8thou to ensure that it was truely flat and to remove a slight 'dish' between No 2 and No 3 cylinders. That done and all back together and it started on the button first time and runs really smooth. Now just got to sort out an airlock in the heater and I'll be off out for a proper test run in what's left of the snow. Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted December 20, 2009 Share Posted December 20, 2009 That's good news Adrian, a slackening of the jubilee clip holding one of the heater hoses to the heater will usually let any air in the heater out. HTH Mo Quote Link to comment Share on other sites More sharing options...
Orange Posted December 20, 2009 Author Share Posted December 20, 2009 After 3 attempts at ridding the heater of it's airlock, I ended up taking the truck for a test drive anyway!! It seems that 60mph down the dual carriageway is an excellent bleeding device!! All is working as it should and all that's left to do now is refit the fan and a quick flush of the oil system tomorrow... Quote Link to comment Share on other sites More sharing options...
western Posted December 20, 2009 Share Posted December 20, 2009 I hope you changed the timing belt while the front cover was off, otherwise you'll be back in there very soon & changing valve pushrods Quote Link to comment Share on other sites More sharing options...
Mark Posted December 20, 2009 Share Posted December 20, 2009 That was where this all started ralph - snapped cam belt.... Quote Link to comment Share on other sites More sharing options...
western Posted December 20, 2009 Share Posted December 20, 2009 That was where this all started ralph - snapped cam belt.... should all be fine from now on then Quote Link to comment Share on other sites More sharing options...
Orange Posted December 20, 2009 Author Share Posted December 20, 2009 Not strictly true, Mark... All started with the overheating, but the snapped timing belt made the whole lot a little more 'pressing'.... Skimmed head, new valves (having bent at least 2 of them), new rocker arms and valve adjuster screws having snapped 4 arms and bent 3 of the screws, new timing belt and updated crankshaft sprocket. Generally a good spruce up and it started first turn of the key and now flies along!! I can even hear the turbo spooling up and the wastegate actuator working.......how novel!! Quote Link to comment Share on other sites More sharing options...
western Posted December 20, 2009 Share Posted December 20, 2009 Excellent that'll be your to self Xmass present then. Quote Link to comment Share on other sites More sharing options...
Orange Posted December 20, 2009 Author Share Posted December 20, 2009 It's actually next year's present!! Got a holiday for this one...!! Need to keep it a little bit quiet until next December!!! Quote Link to comment Share on other sites More sharing options...
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