Cam cover replacement nb fl- need for blobs of sealant on gasket

Technical Area Engine, Transmission, Exhaust etc
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  1. My model of MX-5 is: NB FL
  2. I’m based near: __WORCESTER
  3. I’m looking for technical help or recommendations on: _Need for blobs of sealant on gasket at cam bearing cap to head joints.
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Hi, I have taken the cam cover off to check the tappet clearances and in preparing to re-install the cover I noticed that there were small blobs of sealant at the point where the cam bearing caps meet the cylinder head. The actually appeared to have been squeezed out of the way by the gasket i.e. not doing anything useful. Reading up on this on the Forum suggests this is standard service procedure but I don’t recall doing this when I had the cover off to replace the timing belt about 4 years ago.

So my question is - was this addition of sealant a factory process or a “service fix” for the dealers, or something the owners came up with on early models and has carried over unchanged even though it is not necessary ? My concern is that putting a blob of sealant where it is not needed will only distort the gasket and might cause a leak.

If not - what is the experience by members who service MX5s on a regular basis- is the sealant actually necessary if you use an OEM replacement cover gasket ?

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Yes do use the sealant, hi temp as at the points shown in the pic. Also do use a genuine Mazda gasket replacement part.

Did my NA a few years ago as it was leaking and replaced the CAS seal too whilst there as it’s easier with the cam cover off. Probably a blob at each point smaller than a pea.

TBELT9

1 Like
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Thank you for the prompt response - after I wrote the post I actually re-read the official workshop manual section on timing belt installation for the 2002-2004 model ( I have a copy on CD) and it does indeed say "apply liquid gasket of TB1206B or SH780 to the portions shown in the figure " So either I followed that when I did the timing belt and forgot I’d done it, or I failed to notice it and the factory installed sealant continued to do the job.

Regards
Sunlight

1 Like
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Actually TB1207B - a black silicone sealant or SH780 - a neutral Room Temperature Vulcanising (RTV)
sealant.

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Regarding CAS seal, fortunately the VVT engine uses a small CAS located on top of the cam cover above the rear inlet valve- if the o-ring did leak it is one bolt to remove !