Clicking/Tapping Noise - Exhaust Manifold?

lukewilliam1_75

lukewilliam1_75

Member
Went for a drive yesterday and noticed the 3500s was making a tapping/ tinny noise from under the bonnet! Definitely not what I am used to! Any ideas?

Not sure if it's belt off the alternator?

Or this what I believe to be crack?

Couldn't touch it as I fired it up and still had the noise!





Have read I can by some repair kits that set by heat ect, any recommendations?
 

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That does look like it's holed there, but I have never seen one go there before.
The "tap tap tap" noise is most likely manifold related, though. Nip up the bolts and see if it changes anything, and have
a poke at that place in the pictures with a small, sharp item to see if it si indeed a hole. If it is, don't bother repairing it
as manifolds are plentiful.
 
Remove the manifold locktabs and replace with spring washers. When you knock the locktabs back the chances are you'll find that most of the bolts are loose.
 
That certainly looks like it has a hole in it Luke :shock: If you scrape the paint away, you'll obtain an improved view. Second hand manifolds won't be all that easy to come by locally any more, and sourcing one from the U.K will cost a packet in postage.

If it is holed, then having it filled would be a better choice I would think.

Ron.
 
Ok!

So went around to the club experts place today! As per the photo's not as bad as first thought! There is a small hole, very small hole in my drivers side manifold!

Confirmed this after listening to the engine, and then with a house piece near the area in question on the manifold and then to the ear, you could clearly hear the clicking noise!

Suggested seeing if I can get a replacement, ill try another contact this week, therefore bolt on and bolt off, otherwise need to find a cast iron welder to weld the hole ect!

Said car is still drivable! Just a little more clickety clack then normal!
 

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Harvey wrote,...
Remove the manifold locktabs and replace with spring washers.
Click to expand...

I have tried this with my 4.6 Harvey, but unfortunately the bolts come loose all the time, requiring nipping up every few days. Possibly a suitable medium strength thread locker might provide an advantage if not using the locking tabs.

As it was I went back to the locking tabs, setting the torque when the manifolds were at normal operating temperature, then knocking up the tabs.

Luke, if you run your engine in the dark, flame doesn't come out of the hole I take it? What about if you increase the revs to represent normal driving?

Ron.
 
SydneyRoverP6B said:
Harvey wrote,...
Remove the manifold locktabs and replace with spring washers.
Click to expand...

I have tried this with my 4.6 Harvey, but unfortunately the bolts come loose all the time, requiring nipping up every few days.
Click to expand...

I've never had that problem. Have you got manifold gaskets fitted?
 
harveyp6 wrote,...
I've never had that problem. Have you got manifold gaskets fitted?
Click to expand...

No gaskets although he did use a smear of high temp manifold sealant, as a tiny bit of it can be seen here and there where it has been squeezed out. I commented on it at the time, saying to him that originally there was none used at all. He said he knew that, but would rather be sure than to have a leak.

As it is I am quite happy using the tags. I acquired a NOS set about 26 years ago, so they came to good use. :wink:

Ron.
 
lukewilliam1_75 wrote,...
Are 3500 and 3500s exhaust manifolds interchangeable?
Click to expand...

Hi Luke,

As far as I am aware, there is a difference in terms of outlet diameter, which in turn will influence the size of the downpipes. Prior to 1974, the 3500 manifolds featured the smaller outlets, but from 1974 onwards, the 3500 and 3500S manifolds were the same.

There can also be a difference in the mechanism by which the downpipes attach to the manifolds. My manifolds utilise olives, but I have seen others where such are not employed and the pipes attach differently.

Ron.
 
SydneyRoverP6B said:
lukewilliam1_75 wrote,...
Are 3500 and 3500s exhaust manifolds interchangeable?
Click to expand...

Hi Luke,

As far as I am aware, there is a difference in terms of outlet diameter, which in turn will influence the size of the downpipes. Prior to 1974, the 3500 manifolds featured the smaller outlets, but from 1974 onwards, the 3500 and 3500S manifolds were the same.

There can also be a difference in the mechanism by which the downpipes attach to the manifolds. My manifolds utilise olives, but I have seen others where such are not employed and the pipes attach differently.

Ron.
Click to expand...

Thanks Ron,

I believe Pre-October 1974 build 3500 (auto) wont fit, however in saying that Post October 74 3500 (auto) are compatible with a 3500s..... any any year S model should fit due to having larger diameter manifolds and exhaust system!

I have spoken to a few people today, and they tell me braising/welding on cast iron is a nightmare, and not recommended as it will re crack! Custom manifold is starting at around 1500 plus!

Will need to do some searching and source a 3500s driver side manifold, noticed some 3500 ones on ebay in NSW, thats always the way!
 
lukewilliam1_75 said:
I have spoken to a few people today, and they tell me braising/welding on cast iron is a nightmare, and not recommended as it will re crack! Custom manifold is starting at around 1500 plus!
Click to expand...

If you weld it then it will crack, if you braze it the way I told you then it won't.

lukewilliam1_75 said:
Will need to do some searching and source a 3500s driver side manifold, noticed some 3500 ones on ebay in NSW, thats always the way!
Click to expand...

Both manifolds are the same.
 
+1 to Harvey. You can weld cast iron but its a specialist job... something to do with making a sand mould and heating the sand up repeatedly and letting the item cool over a week or so. very expensive. braising takes a lot less heat and therefor doesn't cause the cast iron to go brittle. However the item to be braised still has to be clean and free from all contaminates including rust!!.
coop
 
sorry meant to say jr waddams do new manifolds for around 200 quid. I know that is expensive especially having it shipped to Australia but probably cheaper than having them welded professionally( if u don't want to go down the brazing route) and definitely cheaper than a custom manifold.
coop
 
If you aren't worried about appearances, put some acetic acid cure silicone bathroom sealer on a bit of flat metal sheet a bit bigger than the hole and fix it in place with a jubilee clip or two.
Try not to squeeze too much through the hole because when cured, the silicone is unaffected by exhaust heat - even right next to the head.
 
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