mx5cartalk.com

Hi, I am about to do a timing belt change on my NA8. Do I need to change the camshaft and crankshaft seals. A colleague of mine, whose views I respect, told me that it is unusual to need to change these seals every 100,000km. They are usually designed for the life of the engine. The point he made, especially for the crankshaft seal is that the one at the front is very similar to the one at the back and that only ever gets changed when it leaks.

So the question is, do we change them because there is a real engineering reason to change them. Has anyone not changed them ?

When it's so much hassle to remove all those bits and put them back on for a timing belt change, why would you NOT do the cam seals and crank seal at the same time? They're cheap as chips and when they do start leaking, you'll have to pull it all down again to fix.

Guran wrote:When it's so much hassle to remove all those bits and put them back on for a timing belt change, why would you NOT do the cam seals and crank seal at the same time? They're cheap as chips and when they do start leaking, you'll have to pull it all down again to fix.

Guran, you make a good point. The counterpoint is that if they are leak free then you are only introducting risk by installing new ones if you dont seat them properly.

snshami wrote:

Guran wrote:When it's so much hassle to remove all those bits and put them back on for a timing belt change, why would you NOT do the cam seals and crank seal at the same time? They're cheap as chips and when they do start leaking, you'll have to pull it all down again to fix.

Guran, you make a good point. The counterpoint is that if they are leak free then you are only introducting risk by installing new ones if you dont seat them properly.

thats a risk, They are easy as to install and fit very snug. Unless you make a complete c0ck of the install, they wont leak.

There is a fair bit of heat where the seals are and they can become quite brittle.

I remember when i did my NB timing belt, the crank seal fell apart when i started to remove it.

for the sake of another $15-25 id do the seals

Just had the lifters done in my NA8A (cams out)and Dalton Automotive did all the seals at the same time, money well spent i think.

Peter.

Agree with the previous posters that it is best to do the seals.

I recently did the 100k change of timing belt and water pump on my japanese import NB.
The seals that came out were still in good condition, but were worn compared to the new ones.

As Bryan said, it seemed best to do the seals while they were easily accessible.
I reckon the risk of a leak from replacing the seals, if done carefully, is less than the risk from leaving them for another 100k kms,

BTW, I hope you are replacing the water pump too?

Hi, thanks for all the responses. I am doing the water pump for sure. I have the seals ready to go and if there is any sign of leaking or weeping or brittleness I'll do them for sure. As far as I know they are not holding back oil pressure and are only to prevent leakage from splashes. Based on your responses I am now leaning more towards doing them.

snshami wrote:Hi, thanks for all the responses. I am doing the water pump for sure. I have the seals ready to go and if there is any sign of leaking or weeping or brittleness I'll do them for sure. As far as I know they are not holding back oil pressure and are only to prevent leakage from splashes. Based on your responses I am now leaning more towards doing them.

If you have the seals do them, it's an extra 30 mins for the peace of mind

Unless they're showing signs of leaking or weeping IMO they are best left alone. If you are going to replace them, use decent Jap style seals or genuines. It's more likely to leak if you use a crap seal than it is if you left them alone.

Cheers
Woz

mechanics often do not just replace items unless there are signs of problems or unless a customer requests it. Sometimes it is better to leave things alone if they are not defective. If an informed colleague gives the advice I suggest just take it- I would not argue with Woz' thinkiing. Either way just make a call.

Thanks for the feedback. I'll have a look at the seals, if there is any sign of weeping or if the seal looks fragile I'll change. I do have genuine Mazda seals.

snshami wrote:The counterpoint is that if they are leak free then you are only introducting risk by installing new ones if you dont seat them properly.

that is a very poor counterpoint. The very well known seal faults with B series engines is the engine cover, dissy/cas, front and back main seals become leaky with age.

Hence most owner choose to change them before they become a problem. It's you choice to do them or not. But for a $17 seal/s, I'd do them at the time of replacing a timing belt.