Hi just bought yam dt 125 1989, done the head gasket and water pump,flushed system out already had bottom end rebuild. but its still got presure in raidiator and its chucking the water out of the expansion tank? will run for an hour the over heats. [doing my head in]any ideas thanks
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Re: presure in raidiator
I know you said you did the head gasket, but it really sounds like a head gasket issue and pressure getting from the cylinder into the colling system. If you've had recurring overheating that necessitated another gasket replacement you'll likely have a warped head, which could explain the recurring t symptoms despite changing the gasket.
I'd do a compression test with the radiator cap off and see if you're losing compression. You'll likely need to have the head machined to remove the warping. Once machined and replaced with a good Yamaha brand gasket and a high temp sealant to help it, you should be okay. Be sure to torque the head bolts exactly in the order required and to the exact level required by the factory.
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Belts only drive the water pump and other accessories and do not cause overheating. Have a pressure test done on the cooling system. Have a compression test done to check for head gasket or cracked head. Have a flow test done to check for blocked cores in radiator .check external fins of radiator to see if they are flaking off. Flushing radiators doesn't work because once the cores are blocked up there is no way to un block them. If you have a viscous fan hub have it check out as they stop driving after a period of time.
you don't say what year caddy. but older models (especially the 4.1L) did have a problem with intake manifolg blockages and gasket leaks. if that sounds like it could be your problem try replacing the intake manifold gasket, and clean out the inside of the manifold while it's off either manually, or by having it put in an acid vat at a rebuild shop or napa center
I actually have the same problem with mine and I finally had it looked at by a mechanic who said that it's either cracked head gaskets or cracked cylinder. Both are costly because of labor involved in getting to the problem. Yours might be the same thing.
if the water pump bearing or seal or bearing has colapsed it is posible for water to find its way into the crankcase. however I must ask did you completely flush the cooling system & change the oil when you changed the head gasket if not the sludge that was left behind would continue to mix with any fresh oil or coolant you may have put in if in fact your problem was a blown head gasket in wich case you need to investigate the cause of the blown gasket have you recently topped up the coolant whilst the motor was hot or worse over heated doing so will definately cause a head gasket to blow was there obvious evidence of the gasket being blown ie blow by marks on the gasket or the head & barrel surfaces if not you will need to further investigate the reason for water finding its way into the oil.Let me know how you get on.Regards Geoff
There could be several reasons that may cause an engine to overheat. It sounds like you have covered the most important ones. Thermostat,radiator and water pump. Hopefully you do not have internal damage, cracked head, head gasket, or a cracked block. I would try flushing the heater core and pay close attention to what comes out. You know, is it clogged with stop leak or rust. Then while I was flushing that I would drain the entire system and put in some Prestone super radiator flush. You just add plain water with it and run your vehicle for about 10 minutes. You then empty your cooliant system and refill with antifreeze. The flush works pretty well and if there is an obstruction from a previous owner putting stop leak in the system it generally will clean it out.
BTW, are you sure the thermostat is in properly? Not upside down? I think I would start there before I went through all of the work of flushing the system. It actually sounds like from everything you've done already, that's possible. Hey it does happen once in awhile. Was this car overheating when you bought it? If so, maybe the previous owner put it in upside down, and when you changed it put it in the same way by accident.
Hope this helps.
did the electric fan on the radiator start up? if this dont start up, it can get the engine overheated , specily if the car run in hot weather , an when the car stay on idle . The other problem is the engine head , the head gasket can blow and you get the compresion presure in the water chanal .Try to se of the oil on engine is gray? If gray you must change head gasket.
Hoope this can help you