Yamaha TRX850 Enthusiasts Forum

Ok guys need some help as I'm about to start tearing my hair out....... I've had my cylinder head repaired and after re fitting it and filling with coolant I noticed a slight coolant leak at the rear left of the head gasket (new head gasket) so I stripped it back down again and had the surface of the head checked and it was found to be a little out of true so I had it skimmed and pressure tested, the guy in the machine shop reckoned he only had to remove 0.05mm to get it right. I've re-installed the head today, torqued the head back down again to 40nm, refitted the cams and filled with coolant left it a few hours and there is a very slight weep of coolant this time from the centre rear of the head It's doing my head in.......I've torqued it down to the correct setting, used a new head gasket and made sure the surfaces are spotlessly clean, what am I doing wrong, I don't want to strip it all down again but I've got no choice. I've used an Athena head gasket and was wondering if anybody had ever had problems with this make of gasket or am I just clutching at straws? Any advice is very much appreciated.
Cheers
Rich

Leave well alone and run some K-Seal in the coolant: http://www.kseal.com/uk/
It `might` be ok after a while and running, settling, re-torqueing.

Mincehead wrote:Leave well alone and run some K-Seal in the coolant: http://www.kseal.com/uk/
It `might` be ok after a while and running, settling, re-torqueing.

I like your thinking mate, the thought had crossed my mind and I've seen some good reports about K-Seal, it just felt like putting a sticking plaster on the problem after having the head repaired and fitting new valve seals and grinding valves back in etc. but I'll give it a go. Meanwhile I've ordered a genuine Yam head gasket so if K-Seal doesn't
work I'll replace over the winter...... Just as a thought, the original head gasket has a very fine coating on it (like a black silicone) and the Athena gasket is just bare with no coating.....wonder if thats the problem?

Personally I wouldn't waste my time and money adding a band aid solution to stop your head gasket woes.
You have gone to all the trouble on the head to get things back to optimum and you have a new OEM head gasket on the way.
Just spend a little time and patience and do it the right way and have piece of mind that all will be good.

And a simple note ...
( this is not directed at you personally cake man ... I'm just stressing this vital point to anyone who removes the cams. )

Cam caps need to be torqued to 10Nm and no more.
Tighten by hand, then to 5Nm and finally 10Nm in a x pattern.
I've seen a couple of Trx motors that haven't followed the torque specs and have had the cam lock due to over tightening the cam caps to the detriment of the motor. Ouch....

Hope your mobile again soon..

cobbadiggabuddyblooo wrote:
And a simple note ...
( this is not directed at you personally cake man ... I'm just stressing this vital point to anyone who removes the cams. )

Cam caps need to be torqued to 10Nm and no more.
Tighten by hand, then to 5Nm and finally 10Nm in a x pattern.
I've seen a couple of Trx motors that haven't followed the torque specs and have had the cam lock due to over tightening the cam caps to the detriment of the motor. Ouch....

Hope your mobile again soon..

I hear what you're saying regarding the cam caps cobba........ spent a fair bit of time tightening them down to the correct settings, also used plastiguage to check the cam cap tolerances while I had everything apart just for piece of mind......for the sake of a few quid it's worth the effort

Well, bitten the bullet and stripped the top end down again, obviously during the strip coolant is on the top and bottom surface of the head gasket but I was really careful to disturb everything as little as possible and when I inspected the gasket there is a load of coolant in between the layers of the head gasket plus the layers pull apart very easily and when I compare it to the original gasket which has covered over 30,000 miles the layers are still really tight.....hope the new gasket solves the problem.

This is one major point that hasn't been addressed much here.
I've seen a few motors that suggest cam bearing failure along with the dreaded oil useage crank failure.
One of the reasons for me to replace my origional motor was to a noisey third and a Kawasaki workshop damaging the left exhaust cam shells...that was ten years ago...(well that AND timing the motor wrong and bending the right inlet valves as well...)..mind, they gave me a ZZR600 loan bike that I hammered and put 5000 Kay up in the month it took to fix my engine.

Hope your mobile again soon..

Good to here you got a good outcome Rich.
Says a lot about the Athena head gasket so a good lesson there for all of us.
I contemplated running an additive to my coolant with the slight weep while using the copper head gasket I had made up.
But running that through the radiator and water pump sounded like a recipe for disaster.
There is a small hole just down by your water pump.
This is here for that very reason incase the mechanical seal fails and coolant will weep with pressure build up through this hole.
So you can see an issue arising straight away.

Nah, K seal don`t work that way mate, it`s not like the old `egg in the radiator` trick.

Problem fixed (at last). Genuine head gasket arrived from Fowlers (Fowlups lol) in Bristol and managed to grab a couple of hours to put everything back together. Re-filled with coolant and all is hunky dory......might even get a chance next week to fire the old gal up

I had problems with an athena head gasket!

buy genuine for all critical gaskets and seals is my advice - found out the hard way!