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Post by pepsisteve on Oct 7, 2010 20:24:20 GMT 1
i cant seem to stop the lc (4lo) leaking water between the head and cylinders (head gasket) i have tried 3 different head gaskets, had the head faced and then had the cylinders faced with them bolted together, all of the machineing was done at a friends engine building company so i can be sure that has been done 100%. but i have just put it back together and it still leaks even with it just sitting on the stand with the engine off it just drips from both sides. any ideas! when it was a 250 it was fine, same make gaskets as well.
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Post by elsie1411 on Oct 7, 2010 21:06:13 GMT 1
just a thought could it be that the studs are not pulling down enough, what size washers have you got on the head bolts?
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Post by gazzatt2 on Oct 7, 2010 22:02:48 GMT 1
make sure it is not the hose at the rear leaking and running around the head
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Post by pepsisteve on Oct 7, 2010 22:23:57 GMT 1
just a thought could it be that the studs are not pulling down enough, what size washers have you got on the head bolts? i dont have any washers under the head bolts! didnt think they had any. plus they are the same bolts that i used on the 250 and the 350 cylinders are taller so it shouldnt be the suds bottoming out.
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Post by pepsisteve on Oct 7, 2010 22:24:33 GMT 1
make sure it is not the hose at the rear leaking and running around the head will check that one in the morning
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Post by oldelsieboy on Oct 7, 2010 22:32:44 GMT 1
just a thought could it be that the studs are not pulling down enough, what size washers have you got on the head bolts? i dont have any washers under the head bolts! didnt think they had any. plus they are the same bolts that i used on the 250 and the 350 cylinders are taller so it shouldnt be the suds bottoming out. 250 & 350 share the same studs & bolts so wont be length of these, also barrels are same height only bore is different. There should be a washer under the bolt, see pic OEB
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Post by winnerevo1 on Oct 8, 2010 0:02:09 GMT 1
just a thought could it be that the studs are not pulling down enough, what size washers have you got on the head bolts? i dont have any washers under the head bolts! didnt think they had any. plus they are the same bolts that i used on the 250 and the 350 cylinders are taller so it shouldnt be the suds bottoming out. You definately need washers and you may need thicker washers than standard or shorten the head bolts if the barrels have been machined. Reason being, the head bolts can bottom out in the bolt hole of the barrel meaning it won't be pulling the head down. An easy check is remove head, screw in the bolts as far as they go then measure the gap between the top of the barrel and the head of the bolt. Next, measure head and gasket thickness (used one) and if this dimension is smaller than the one above then there's your problem.
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Post by winnerevo1 on Oct 8, 2010 0:06:08 GMT 1
the 350 cylinders are taller so it shouldnt be the suds bottoming out. It's not the overall height of the barrel that is important, it's the depth of the counterbore from the top face of the barrel.
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Post by pepsisteve on Oct 8, 2010 11:29:49 GMT 1
thanks for all the replys guys, just got back from the engineers and he said looking at the head gasket it has had insurficiant clamping force. so it would seem we are in the right area. found another set of spare bolts in my box of bits and they have washers on them, so i will do the measuring thing tonight and report back.
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Post by mark350lc on Oct 8, 2010 13:07:34 GMT 1
Are you using genuine Yamaha gaskets or pattern ones? I have had mixed results in the past with pattern. I only use genuine now.
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Post by pepsisteve on Oct 8, 2010 14:22:22 GMT 1
i know what you mean about the pattern gaskets mate, but i use a good quality pattern one and they seem fine. after all the replys it would seem i have a clamping issue as last night after having the cylinders lightly faced i didnt even get to start it up before it was having a little wee on the floor, so by having them faced i made it worse.
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