2.5L ('98-'01) Valve stem seals - are standard and "top hat" interchangable

[RJH914]

New to forum - love these trucks!

I'm rebuiding a cylinder head for a 2000 Mazda B2500. The gasket kit I bought included the "top hat" design valve stem seals while the originals were the regular design. I didn't think much about it until I installed the top hats & realized that they would compress the valve spring by about an additional 1/8" when installed. Are these interchangable? Am I OK to use these or should I pop on an original set of stem seals. Pics attached - 1st pic shows old seal, 2nd shows top hat and 3rd shows how valve spring rides on top hat when installed. Thanks in advance.

 

[alwaysFlOoReD]

I'm not sure I understand how the top hat seal will touch the spring to compress it. I could see maybe the top of the seal touching the keepers but also find that very unlikely unless you've had major valve work done or changed lifter ratios.

 

[RJH914]

I'm not sure I understand how the top hat seal will touch the spring to compress it. I could see maybe the top of the seal touching the keepers but also find that very unlikely unless you've had major valve work done or changed lifter ratios.

Thanks for the reply. The engine is completely stock - I installed new exhaust valves and lapped all the valves in. Check out the 2nd pic - the "brim" portion of the top hat rides in the recess where the valve spring normally rides. With the top hat design the spring rides on top of the "brim" area, not in the recess anymore...compressing the spring more than with the regular seals in pic #1.

 

[alwaysFlOoReD]

Ok. I've never worked on a 2.3 yet. But I've rebuilt several engines. So the spring sits on top of the shoulder ( brim) I see in the 2nd pic? That doesnt seem right. I would expect that shoulder to register the spring so it doesnt move sideways while engine operation. In other words I would expect the spring to slide over that shoulder. Is there a gap under the spring? Can you show a pic of the top hat style not installed?

 

[RJH914]

Wanted to follow up on this in case anyone else ran into the same thing. It looks as if two different styles of valve stem seals were used on the SOHC 2.5L engine. My research suggests that they are NOT interchangable. The "top hat" design causes the spring to ride on the ridge of the "hat" which causes it to compress too much when installed. The Haynes manual calls for 1.54" to 1.58" length when installed. When installed with the top hat seals, it only measures 1.36". I've ordered a set of standard seals. Attached are pics showing the problem.

 

[alwaysFlOoReD]

Interesting . Thanks for the update.

 

[scotts90ranger]

I've never seen a valve stem seal like that...