The LT500 (1989) that i just bought has a problem with the cooling system. The water pump seal appear to be leaking so I installed a new one, I found the engine had very little water in it when I drained the system. Filled system with 50/50 mix, bled the air on top of the head and fire the engine. The cooling system builds pressure up in a hurray, blows water out the water pump bleed hole and the overflow bottle. If you start the engine with radiator cap off it shoot water 3 feet when the engine starts.
No evidence of water in the tranny, no water comes out the sparkplug hole kicking the engine with the plug out, no steam from the exhaust pipe....
What do you guys think??

 

i dont know whats on the 500r, is there hoses, a radiator? if theres hoses pull them and see if they are not cloged up or went flat. the radiator may also be cloged up. it just sounds like a major block in the system.

 

COOLING SYSTEM PROBLEM UPDATE Drained the system, pulled the head. Gasket was blown and in very bad shape. The piston was in good shape but the connecting rod has a lot of slack in it. So I pulled the cylinder off. Rod is definetly loose on the crank end.
Anyone have any suggestions as to a shop to use for repairing this beast?

 

I was going to suggest the head gasket. The compression inside the cylinder is obviously leaking into the cooling system which definately sounded like the head gasket. The cooling system shouldnt pressurize. The only pressure in the system should be the expansion of the cooling liquid when it starts to get hot. Mine had the same problem with the pump gasket as well. Ive ordered a new one so hopefully thats the end of that problem.

 

You have to pull your motor and split the cases. The rod on my 1986 Yz 80 was loose, but I thought it was okay being like that. I was wrong, I then blew the engine, and pieces of the bearing came up into the cylinder. It ruinmed everything, including the cylinder bore, piston, head, crank and connecting rod. I got it fixed for under $500. (I did the work my self) I dont know the exact breakdown, but a new crank and rod should run about $200. I'd go with that instead of having a shop split the crank and then put it back together. Just my thoughts. . .

 

here is my solution, i've been using it for quite some time and havent had anymore problems with leaking coolant into the cylinder..

get the head O'Ringed... its well worth the money you'll spend. my dad and i have it done to all our LT500 motors.
its easier done on the 87 motor, but can be done on the 88+
it all depends on if you have oversize head studs (something else we do)

as far as the rod feeling loose, you may need to rebuild the crank and put new bearings in.

 

LT575

I too had my head o-ringed. This has proven to be the best solution. No problems in 2 years.

 

hi guys. After you get the head o-ringed, do u have to replace the o-rings each time you remove the head? Or are they good for a long time? Just wondering. I hate payin the dollars for the gaskets!

 

i've used my o rings for a long time, they are re usable, just dont pinch them when you put the head on.. i use a little bit of hi temp rtv silicone adhesive to stick the o ring in the groove so it doesnt fall out when putting the head on.

u dont have to put silicone all around the groove, just a few spots to hold in the o ring. make sure u have the right o rings. the inner one needs to be hi-temp

 

Where are you guys getting your head o-ringed? What does it cost? Thanks