Sealing manifolds to y piece

[Belle427]

I have an annoying chuffing from the manifold to y piece joints, the fit isn’t bad but there is enough of a gap to not seal properly.
I can get the clamps on ok without having to pull manifolds about so alignment isnt too bad.
I have standard manifolds and a Clive y piece, I have tried exhaust paste but it sets hard and tends to crack and fail.
I was thinking of trying silicone sealant of some description, I have no cats to damage but do have a wideband lambda installed. I could remove this to run the engine through a few cycles.
Has anyone used a more flexible exhaust sealant they could recommend or care to comment on the silicone route?
Maybe something like this would be ok?

https://www.toolstation.com/mapeflex-firestop/p421...

Edited by Belle427 on Saturday 16th May 18:18

[Macbags]

Hi

I fitted a Clive F ypiece to standard manifolds a couple of months ago and initially had the same problem. I found the original clamps a poor fit and having over tightened one in an attempt to seal the connection i sheared the clamp bolt..... I ordered two replacements from Dom. The replacements were a far better fit and allowed for better fitting before tightening the bolts.

I added paste between the nanifold and y piece., aligned them and then gently tightened, leaving them overnight before curing before running the car up to temp. It worked for me and I now have an airtight seal.

I’m not sure a silicone based sealent will deal it’s the temps?

[Belle427]

Yes the temps are an issue, I’m going to give this stuff a try in the hope it stays a bit more flexible.
Passenger side fits well but then when tightened leaves a small gap in the drivers side, I’m not going down the route of loosening manifolds as it will put stress on the head side when tightening back up which I want to avoid.
https://www.ebay.co.uk/itm/251646614287?ViewItem=&...

[cp81]

I would be interested to see how you get on with it. I have similar small leaks, with brand new clamps... very frustrating.

[bobfather]

I found that tapping around the ring clamp with a hammer while tightening the clamp nut worked great. Every hit with the hammer resulted in an easy turn on the nut. Keep doing it until there's no more turns on the nut and you should be very well seated