Help...any Ideas

dirtbikedad · Apr 28, 2003

Help... anyone... My son's 97 CR125 has a reoccuring problem. It is pressurizing the the cooling system, causing the coolant to bypass the new pressure cap and vent through the overflow tube. When the cap is off and the engine running, I see lots of small bubbles rising to the cap inlet. I presume this is due to a blown head gasket. I have changed the gasket, had a machine shop surface the head and cylinder, and carefully torqued the parts together twice. Both times the bike worked for about 5 hours then the problem surfaces.

The cylinder has a steel sleeve that was installed before the first boiling problem.

Can the cylinder have a crack the allows air to get to the water jacket? None are visible.

Any other causes?

Jerry

Eggnchips · Apr 28, 2003

It is probably the head gasket. If the head has been checked for warpage, then it is either improper fitting of the head gasket or there is an imperfection on the top of the barrel.

When fitting the head gasket make sure there isn't a single trace of old gasket, oil or water or anything else on either mating surfaces. Give the surfaceas a very light polishing with very fine wet & dry soaked in WD40 until the surfaces shine. If you clean the mating surfaces properly and torque down the head properly then you should not need any kind of gasket sealant.

Joepro9 · Apr 28, 2003

are you sure it air bubbles and it not over heating? those boke will overheat fairly fast if you leav them sit and running. Any there any other coditions or variations? maybe a hose clamp is loose? those are steel gaskets on the head too.....

Help...any Ideas

dirtbikedad

Eggnchips

Joepro9

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