Exhaust manifold gaskets V8

[ozscott]

Just a quick note about exhaust gaskets. When i did the head gaskets on the 4.6 I used new multi layer steel (stock) gaskets on the exhaust manifolds. I noticed a ticking on the driver's side a few months after the rebuild. I thought it was exhaust but it sounded like tappet also.

I decided after the sound got a lot worse during the 6000k return cape trip to have a look and indeed the bolts near the firewall were not tight. Nipping up didn't help too late.

I took off the manifold. Sure enough the gasket was stuffed. The best way to get the 2 steel gaskets on and oriented the correct way is to lever the manifold away from the head and then stick a block of wood between motor and middle of the manifold then put gaskets with bolts in place and then remove wood and hand tighten a few top bolts then all bottom bolts then remaining top bolts.

I tightened the bolts in proper sequence per RAVE at 12 ft lb then 28 but this time I went to 33 ftlbs...hopefully they will stay tight but I will go around and check each week for a few weeks to make sure they are tight after the gaskets are bedded down .

Cheershttps://www.aulro.com/afvb/images/imported/2017/07/577.jpghttps://www.aulro.com/afvb/images/imported/2017/07/578.jpghttps://www.aulro.com/afvb/images/imported/2017/07/579.jpg

[Roverlord off road spares]

This is from RPI with the old single gaskets, I wonder if it also applies with the shimmed joined gaskets used on the later V8s.
I also notice some exhaust places smear a bit of high temp RTV on the gaskets faces.





https://www.aulro.com/afvb/images/imported/2017/07/592.jpgExhaust gasket alignmenthttps://www.aulro.com/afvb/images/imported/2017/07/240.jpg (http://www.v8engines.com/engine-4.htm#top)



https://www.aulro.com/afvb/images/imported/2017/07/593.jpg Although it may seem obvious, which way round you fit the exhaust gaskets, it is very possible to get it wrong, We strongly suggest you check [& double check] the correct alignment as the following 2 pictures will show, getting it wrong has serious power loss implications.



https://www.aulro.com/afvb/images/imported/2017/07/594.jpg

https://www.aulro.com/afvb/images/imported/2017/07/595.jpg



It's clear to see just how wrong things can be. The problem is not 'the wrong way round', but 'inside out & the wrong way round'!




Surprisingly enough, exhaust blow was not a problem but power was 40% down (minimum), especially as rpm. increased.

[ozscott]

Thanks Mario. RAVE calls for dry. This time I used Permatex gasket maker. Not the high temp silicon RTV but the smelly black goop. I make very sure to get them the right way. The best way is to wedge the manifolds off and once gaskets are placed just feel with a finger to ensure gaskets edges are flush with the edge of the manifold port. Cheers

[Roverlord off road spares]

Yep there's not a lot of meat on the manifold outlet edges.

[bee utey]

I would consider checking the tightness of V8 exhaust manifold bolts to be a regular maintenance item, especially after a replacement engine. They are fairly easy to get at after all. I lose track of how many chattery LRV8's have come in here that got much quieter after 10 minutes with a socket and ratchet.

[ozscott]

Just checked the bolts. The most rear one under manifold near firewall (driver's side) was quite loose after a drive today...torqued it up whilst still warm to 35 pounds and marked all bolts with a permanent marker to keep an eye on them. This engine is so smooth and sweet when the manifold is bolted up tight! Cheers

[Pedro_The_Swift]

mine makes an exhaust leak noise at full load,, sorta. you can hear something compressed leaking somewhere, but all manifold and joints are tight,,
yea, I remember getting schooled on the single gaskets last time,, the ports are that small to begin with,, they dont need any extra blockage...

[Roverlord off road spares]

Just checked the bolts. The most rear one under manifold near firewall (driver's side) was quite loose after a drive today...torqued it up whilst still warm to 35 pounds and marked all bolts with a permanent marker to keep an eye on them. This engine is so smooth and sweet when the manifold is bolted up tight! Cheers
The D1s had locking tabs that belt over the bolt head to stop this happening. Then they changed on the D2.