Steve mac

All I am now completely puzzled, New thermostat (G) has made no difference. Here's what happens, First 10miles or so running at approx 60-65mph temperature is normal (half way) on gauge, for no reason it then climbs to nearly 3/4 and stays there until switched off. I put the old stat back in and it runs cold. New stat back in again and it runs hot as above. Radiator and Waterpump been in for a year. Regards Steven Any ideas or don't worry about it.

Thanks all for responses. Genuine part on the way.

All I am having Thermostat reliabilty and and consistency problems, I have been through 3 in a year. I Have a 1995 300tdi 90 in which I put in a new radiator, waterpump and thermostat, a slight lack of concentration and the gauge was in the red blowing the head gasget, Possibly an air lock but when I tested the thermostat it did not open until the water in the pot had been boiling for about 3 minutes ( I know I should have tested it before putting it in). New Head gasget and all put back together except this time with the old thermostat because I knew it worked, sort of. because of the new Radiator etc the engine temperature struggled to get off the bottom of the gauge. That was fine for the summer but i wanted some heat in the cab so bought another one 3 weeks ago. This one runs at 3/4 on the gauge and I have checked for airlocks etc. I don't feel comfortable with it running at 3/4 based on what has already gone wrong with the poor girl. Question. Can any of you recomend a good quality, reliable brand of Thermostat. Many Thanks Steven

Many thanks to all of you that have replied.

Thanks all for responses. Paddock kit was used. I only needed to replace one ball and that is the one with only 1 shim, The ball was part of the kit, I,m guessing from some of the responses that the kits are notoriously rubbish? Maybe I'll leave it a while to see if it gets any worse and then get some decent taper bearings. If the seal is removed to check the preload how much one shot can i expect to loose?

I have just replaced the Swivel Balls and Bearings on my defender and set them to the correct preload, It felt 100% for about the first 100 miles and now the dreaded wobble seems to have returned. It is only very slight but annoying as it was 100%. Can you check the preload with everything on apart from wheels and brake callipers or does it all have to come off again. If it can be done what is the approx preload. One other thing is that when I replaced the balls one of them only required one shim (the thinest). does that seem right? Cheers Steven

Grant Have you tried listening in the engine bay and reving the engine. I had a horrible noise when I accelerated and got over 20mph which was mystifying me. When I lifted the bonnett and reved the engine I could hear it was coming from the engine bay somewhere. It was suggested to me that I remove the 300tdi serpintine belt and then start and rev the engine. Noise disappeared. It turned out to be a shot bearing on the alternator. It sounded much worse than that while i was driving though. Try it, it might be a quick fix. Steven