[vicmac]

Hi! My 1983 MCI MC9 coach started using a gallon of coolant (which I figure is about a teaspoon a mile) about 8,000 miles ago. It does not seem to have gotten any worse during that time. The engine starts normally, does not leak any coolant while sitting for a month, and has clear, dark oil which goes down normally (about a gallon in 1200 miles). Fuel economy and horsepower do not seem to be affected much. There are never any green drops under the bus, and there is no visible green "goo" on the engine.
I am assuming that the coolant is leaving through the exhaust. It seems like the top suspects are (1): A leaking injector tube OR (2): a crack in the head between a water jacket and an exhaust port.
Someone has suggested I might want to try a block/head sealer (Like Bar's Leaks HG1). HG1 can be used in antifreeze, and contains carbon fibers. Does anyone have any advice on that? I wouldn't mind replacing a head, if I could figure out which one needs it. What else could it be? ? ?

Thanks for taking the time to help!

 

[Gone Fishen]

Do NOT use any of that crap sold for 'leak fix'. The stuff coats the head surface and plugs the coler cores. Yes I have seen it. You have several options and none are good. 1 the weep hole is plugged on the waterpump and this allows coolant to enter the oil pan. 2- engine has sat for a long while and the coolant has NOT been maintained or circulated. This allows rust to accumulate on the head/block seals and again allows coolant to enter the oil pan area. There could be a leaking upper injector copper and again this allows coolant to enter the oil pan. These are the easy ones. The 92 series will NOT tolerate contaminated oil from the cooling system. The mainbearings will spin and take out the crankshaft and even the block.
Now the fun part, drain the oil, remove the oil pan. Pressureize the cooling system to 10 psi. Start looking for coolant. If it comes from the front RS then it is the waterpump. If it comes down any of the sides look to be sure it is coming from the head-drain holes and NOT the liner/block area. If it comes down the rear flywheel housing are it is the aircompressor. If it comes down the rear of the engine block in front of the backing plate then it is a leaking head seal.
Get it looked at NOW. 2 cycle parts are not cheap anymore.