Oil leak at the front of my rear bank cam cover gasket on the lower side (happily the one on the front head seems OK) Yet again the very end of the gasket has squeezed out at the front corner. I'm not sure why it happens but it does. Maybe a bit too much RTV bridging the gap between the gasket & the cam seal housing O ring? Either way, I've seen this before - torque the cam cover down carefully & leave it for the RTV at the Cam seal O rings to set for 24 hours. Then as soon as you heat cycle it the gasket squeezes out at the corner. Last time I changed it I watched it happen the first time I ran the engine. Any suggestions as to what to stick the bloody thing down with so it doesn't move? I was considering a dot of good old superglue.
Hmm, I did this job last summer and didn't experience that problem at all. For reference, I used Mazda Grey RTV, because it's really outstanding stuff, and I only used a booger-size blob of it at each corner of the O-ring. For the gasket dressing itself, I used blue hylomar, and I let it get nice and tacky before even touching it to metal. I hand-tightened the fasteners down, and waited for it all to set-up (most of a day) before tightening to spec. I got no squeeze-out from the gasket, and no subsequent movement on heat-cycling. And, most importantly, no leak--even though I am running 0W-50 full syn that constantly reminds me how many gaskets on this engine I *haven't* replaced yet.
Take a sharp punch with a pointed end, put a bunch of dimples on the very end of the valve cover where you are having that problem. The sharp dimples will keep the gasket from squeezing out.
This does work in stubborn cases. I have found..while torqueing down the covers..I use a finger to be sure the gaskets does not move. 8-10nm is all they need. Some folks over torque. Under heart expansion that torque will increase. If to much torque..the gasket will get sqeezed too much and end up being pushed out. Bottom line..stick to the factory torque spec and you will be fine.
I've had some engines that play nice and don't leak. Conversely I've had others that I threatened to weld shut! The warpage factor is high on many as over the yrs they've been over tq'd. Doesn't take much to hold them down and doesn't take much to warp them as well. Dot dab of rtv in the corners is all that's needed. More importantly though is trimming and cutting the gaskets to fit, esp if using GT gaskets.
A lot of factors to consider. With RTV you just need to be prudent and understand the properties and behaviors of the product. With torque you really need to be patient. Kind of sneak up on it. But then there's the real bogyman of quality. On older cars like the 308 you are forced into aftermarket and while some products may be superior to OEM some might not and it's a bit of a crap shoot. You would think that with the invention of the internet that would all have been solved but alas 90 percent of what the internet tells you appears to be wrong. So what can you do?
On mine I've had the cam covers off several times over the years. Always used Hylomar Hylosil 100 series sealant on the face adjacent to the O ring, with cam cover nuts torqued to spec. This stuff seems to hold the joint in place and is a gap filler. Don't advise using it along the complete face - its not easy to remove!
Thanks for all the ideas. I've always torqued them carefully to spec & I've used plain RTV in addition to some other loctite sealants (can't recall the number) - and always used sparingly (or so I thought!). Almost seems to me that some of these things acted to assist the gasket moving rather than sticking it to the head/cam cover. The dimples in the cam cover makes some sense but seems a bit extreme, I'll think on that The idea of welding the thing shut appeals though!
Whatever my coolant manifold gaskets were glued in place with (possibly from the factory) was damn near impossible to remove. Literally the most annoying job I've ever done on this car. The stuff was harder than the aluminum. It was like trying to scrape dried concrete off a stick of butter--without making a mess.
