kevin bryant Posted February 23, 2009 Report Share Posted February 23, 2009 On the longer trips if we sit at 3,800rpm (overdrive 4th) the water temperature starts to rise. Drop back to 3,500rpm and the temperature gauge responds, dropping back to normal. We were thinking that the addition of a heater (mainly for us) and a new water pump (and perhaps a new oil pump) might do the trick and enable us to travel on the motorways a little faster. Any views? regards kev Quote Link to post Share on other sites
marko Posted February 23, 2009 Report Share Posted February 23, 2009 That sounds like a water pump problem to me - or perhaps you have a "hot spot" from a build up of crud around the liners? Quote Link to post Share on other sites
Menno van Rij Posted February 23, 2009 Report Share Posted February 23, 2009 I agree with Marko. When things were normal in the past, his suggestions are very relevant. There's a lot to find on the forum about partly blocking off the waterflow next to the thermostat housing. In short: a lot of coolant never reaches the radiator, it's being detoured (?? correct English?) through the hose on the LH side of the th/housing. Last weekend I had the chance to have a look inside the thermostat housing of a TR4A: The TS-guys knew that there was a problem: the exit on the LH side of the housing was already blocked off, leaving a oblong space for the water to pass. The housing on my TR3A (with early TR4 engine) doesn't have this small oblong space: it has a much larger space for the coolant to pass. Menno Quote Link to post Share on other sites
PatB Posted February 24, 2009 Report Share Posted February 24, 2009 Partial blockage somewhere I'd suspect. Clear enough to handle certain loads but backs up the system under higher rpm. The only time I've noted a temp variation is due to load i.e. a steep hill on a hot day will make it peg a bit higher or redlining it (max capacity) but as soon as you level out/lift the foot some it'll almost immediately drop down. 3800 in 5th for me is 99 mph so you must be cruising. Quote Link to post Share on other sites
Bully Posted February 24, 2009 Report Share Posted February 24, 2009 A common blockage spot on all early TR engines is behind No4 cylinder (furthest away from radiator). Story goes, when people drain the water from the cooling system, they only use the tap at the base of the radiator, and forget about the drain tap towards the rear of the block, under the exhaust manifold. Unfortunately the connection to the block is high up, and this method does not drain anything from the block itself. Sediment then builds up towards the rear of the block. I had this problem many years ago, and ended up removing the head, and fishing out sidiment between the liner and block with a bent coathanger !! I would suggest flushing you block first, and seeing what comes out of the block drain hole. Also worth a fish around with the end of a cable tie (quite stiff and flexible) to loosen any sediment. Cheap and quick to try if nothing else Quote Link to post Share on other sites
Tr4Tony Posted February 24, 2009 Report Share Posted February 24, 2009 Another possibility is that your head gasket is moving around as the pressure builds, so you may have a broken or loose stud which is allowing water to escape ..... check this first as i have seen this on a TR4a. Replacing the stud if its stripped or broken usually sorts this out. Regads Tony Quote Link to post Share on other sites
67_gt6 Posted February 24, 2009 Report Share Posted February 24, 2009 (edited) I agree with Marko. When things were normal in the past, his suggestions are very relevant. There's a lot to find on the forum about partly blocking off the waterflow next to the thermostat housing. In short: a lot of coolant never reaches the radiator, it's being detoured (?? correct English?) through the hose on the LH side of the th/housing. Last weekend I had the chance to have a look inside the thermostat housing of a TR4A: The TS-guys knew that there was a problem: the exit on the LH side of the housing was already blocked off, leaving a oblong space for the water to pass. The housing on my TR3A (with early TR4 engine) doesn't have this small oblong space: it has a much larger space for the coolant to pass. Menno I jammed a bolt into the outlet so that the only route for the coolant is between the sides of the bolt head and the circumference of the outlet pipe. Works a treat, after a long hard run the metal bypass pipe under the inlet manifold is only pleasantly warm. I feel this is easier than manoeuvring drilled disks into the rubber hose and keeping them there etc etc Andy Edited February 24, 2009 by 67_gt6 Quote Link to post Share on other sites
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