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HI Guys,

Been building a 1.6 with my brother and we have had some crazy ass issues with the sump.
We have put together another simple 1.6 build and had no issues but with this engine it has been nothing but dramas.

This is the 2nd time we have tried to install the sump with brand new half moon seals and had this happen at the Rear of the engine.

Basically after we torque down the sump evenly going around and around by the next morning the seal has ballooned and is sticking out like the pictures show!






I am at a loss as to what we could be possibly doing wrong.

Any help would be much appreciated!!!

Hi.
There are two different seals for 1.6 sumps apparently. The gasket set I purchased sometime ago had two sets of seals both different. As it was sometime ago I think one set is thicker than the other. My son put the sump on and commented about them at the time and put the thinner ones on. Have had no problems.

Thanks for the input but I am aware of the 2 sizes.

A fat one for the front and a skinny one for the rear

We also had no issues on the last engine.
Has me stumped what is happening here.




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Guess you are using original Mazda seals?

No, these are aftermarket.
We used the same ones on the last engine without drama.

Not sure how aftermarket could make this happen but am more than happy to understand?





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Goop on neoprene seals is not a good idea, they should seal without it and it sometimes causes the problems you're having by letting the seals slide out of position

Sailor wrote:Goop on neoprene seals is not a good idea, they should seal without it and it sometimes causes the problems you're having by letting the seals slide out of position

Really??
WOW! I actually voiced my concern on using the stuff thinking whats the point of the Seal if you use RTV anyways but the Rod Grainger MX5 Bible says to use RTV under the Seal and all around the Sump.

Perhaps this is the issue??

I've never built an MX5 engine..yet, but on anything I've done I use just a dab of goop near the ends of the seals and only a thin film on the sumps.
Had a similar problem on a valve cover seal when I bowed to pressure and used goop...big job to clean it all up and use just a light film of engine oil to get a perfect seal.

^ this, exactly.

Edit: and then it turns out I'm wrong (again ). From Mazda's factory workshop manual:



and

manga_blue wrote:^ this, exactly. From Mazda's factory workshop manual:

that is for a rear main seal. not the half moon seals in the OP.

project.r.racing wrote:

manga_blue wrote:^ this, exactly. From Mazda's factory workshop manual:

that is for a rear main seal. not the half moon seals in the OP.

Buggar, I recognised that and went back and corrected it in my post and you got a post in in the mlddle.

So it does take sealant all around and under the rubber seals??

Can not even guess why they keep popping out

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Hi.
Looks like you only apply sealant to one side of the seal. You are using too much from your photos which could be the reason for bulging. If it was me I would get genuine seals and start again. You don't want to repeat the exercise sometime in the future.

ralt wrote:Hi.
Looks like you only apply sealant to one side of the seal. You are using too much from your photos which could be the reason for bulging. If it was me I would get genuine seals and start again. You don't want to repeat the exercise sometime in the future.

nope. sealent on both sides and double hit on the pan side of the seal. as per above pic.

if the sealent is left too long before slamming al the parts together, it can become grippy. dunno if this is relivent to this situation.

Thanks all for your input.
We only allowed the time of applying the sealant before it went together.
So prob 10mins max from starting to apply to lowering sump onto block.
Then another 10mins max to torque it all up to finger pressure only.

Both times within one night the rear seal just pops out like that.

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