BMC 1500 / T90

[alb40]

I have a BMC 1500 (Thorneycroft t90) that i have been rebuilding after it went pop.

I have a brand new cylinder head to fit which has cast iron valve guides. I have been told that i shouldnt fit a positive oil seal to the valve stems or they could sieze and cause damage. Apparently, they should changed for bronze guides in order to fit a positive seal.

If this correct? Or do i need to fit a deflector type oil seal to the iron guides?

I would appreciate your thoughts

Thanks,

Alex :confused

 

[FlyingDutchman]

Why do you want to apply positive oil seals?
If the cylinder head has cast iron valve guides, it is appearantly designed like this.
I know many older car engines with cast iron guides that use no oil seals and they appear not to use oil?

 

[alb40]

The old head had positive oil seals and the gasket set contains them also. The old head had bronze valve guides though

 

[FlyingDutchman]

Hmmm, now I am confused too...

 

[dickh]

I too have just rebuilt my T90 head, it had CI valve guides, with seals, so just fitted the new seals in the gasket set. Never heard of positive valve seals.....

 

[alb40]

Just to clarify for everyone, by positive seal i mean seals which fit on the guide to stop oil running down as opposed to the o ring type seals which only deflect oil running down the valve stem

the positive seals are what i have in my gasket set. they are cup shaped with a spring that holds them tight to the valve stem. Are these the sames as yours richard?