Check your Manifold

[trigolf]

Morning all, 

Recently, on returning from a run, I have noticed my clothes were smelling slightly of petrol fumes. Numerous checks were made for fuel leaks from cars and pipework etc, but I couldn't find any. However, after removing the carbs and heatsheild, this is what I found! Strangely, the engine didn't seem to sound any noisier than normal, maybe it's my hearing! If you have a heatshield fitted, it might be worth a check. 

 

[68vitesse]

Had several exhaust manifolds crack on my Mk1 2L Vitesse, can sound like a noisy tappet. Having read about the problems welding cast had one done professionally but have yet to reuse that manifold. Told me he enlarges crack and tig welds using a cast stick electrode with the flux removed as the filler.

Regards

Paul.

[trigolf]

I've read about cast iron welding - it seems to get mixed reports. 

I've got a good spare manifold, just need to get it sandblasted and painted first. Any recommendations on a good heat proof spray paint? 

Has anyone managed to wrap the standard cast manifold with exhaust wrap? Being an akward shape, it doesnt look like it's possible to do a proper job, compared to an extractor manifold. I'm just curious if it's possible, all in an effort to reduce underbonnet heat😕

Gav

[NonMember]

I think if you wrap the manifold it will promote cracks. You may even be better off fitting the spare as it is - don't blast it and don't paint it - because the blasting may expose micro-flaws that will then become cracks, and the paint (especially the black stuff) radiates the heat into the under-bonnet area thus making your underbonnet heat problems worse.

[Colin Lindsay]

1 hour ago, trigolf said:

I've got a good spare manifold, just need to get it sandblasted and painted first. Any recommendations on a good heat proof spray paint? 

Try any of the motorcycle exhaust treatments; I used to use one called PJ1 Fastblack which was a lovely matt black finish (and a lovely smell too!) and especially for motorbike exhausts (which are always on display compared to car exhausts).

 

[Stratton Jimmer]

Back in 1977 my GT6 Mk1 (RPK67F) had a crack develop on the exhaust manifold. My dad who was a coded welder and qualified to weld cast iron using Eutectic's patented methods welded it up for me and it was as good, if not better than new.

[DerekS]

I worked in the chemical idustry and frequently had to have cast iron welding done. Two main points were in preparation, get a good vee groove ground deeply in and, if possible, drill a small hole at each end of the crack to stop it spreading as it is being welded. Preheating can help, too, but again not always possible. And yes, it is definitely an acquired skill.

Derek.

[johny]

Is the fuel smell definitely coming from the crack as there looks to be some staining from elsewhere or is that where youve washed the area?

[trigolf]

That's just Plus Gas penetrating oil to release rusty nuts!

Non-Member makes a good point about sandblasting and micro cracks. I think I'll wire brush it and paint with silver, rather than black, high temp paint?

[foshi]

used chemical metal putty on my vitesse 1600 seemed to work well for the time i owned it just over a year, not sure how good long term though,

[Ian Foster]

Gav

I used QSE Metal Blast on the Nuffield Estate, Poole. Blast and aluminium spray coating. It's holding up well.

https://www.metalblastdorset.co.uk/

Ian

[PeteH]

You have to be very good to acheive a result with cast welding, pre heating is an almost mandatory requirement, certainly to obtain the best outcomes.

Good "coded" welders command great respect, I`ve seen some, in and out of the Petrochem industry. And some who I would not give time of day to as well.

Pete

[trigolf]

34 minutes ago, Ian Foster said:

Gav

I used QSE Metal Blast on the Nuffield Estate, Poole. Blast and aluminium spray coating. It's holding up well.

https://www.metalblastdorset.co.uk/

Ian

Hmm. That's interesting. Can you remember roughly how much? I'm retired now. Don't mention fuel bills!

[Ian Foster]

15 hours ago, trigolf said:

Can you remember roughly how much?

Sorry Gav but it's not an invoice I have kept. Wasn't a great cost IIRC.

I'm sure they will give you price over the phone.

Ian

[rulloyd]

Im sure this will have come up often but what’s the view on ceramic coating? 😬

Rich

[JohnD]

For a good appearance, excellent.  To keep heat in the exhaust gases, rubbish!

May be useful in F1, but not for a road car.   Consider: the ceramic tiles on the Space Shuttle, that protected it from a similar thermal gradient as in and out of the manifold.neededbto be six inches thick.  fraction of a millimeter of ceramic won't keep your engine compartment cool.

Anyway, with an engine less than 40% efficient, the rest of the energy from fuel  comes out as heat through the radiator.

John

[rulloyd]

1 hour ago, JohnD said:

For a good appearance, excellent.  To keep heat in the exhaust gases, rubbish!

May be useful in F1, but not for a road car.   Consider: the ceramic tiles on the Space Shuttle, that protected it from a similar thermal gradient as in and out of the manifold.neededbto be six inches thick.  fraction of a millimeter of ceramic won't keep your engine compartment cool.

Anyway, with an engine less than 40% efficient, the rest of the energy from fuel  comes out as heat through the radiator.

John

Fortunately is looking nice I’m more interested in!  But expensive.  
I’ll start a new thread on manifold paint although I guess it’s been talked to death before.

[chrishawley]

2 hours ago, rulloyd said:

but what’s the view on ceramic coating? 

Did ceramic on one of mine - more out of curiosity than expectation. No real world benefit on heat. Comestically looked lovely for a bit, but after a few hundred miles the appearance reverted to 'standard manifold'.  Done by a high end specialist not some micky mouse outfit. Wouldn't bother again.

 

 

[Wagger]

Cast manifolds will not rust away before they crack. I would use the motorcycle black or nothing at all. Good welders of cast iron are hard to find.

As PeteL says, check that something else is not leaking fuel. Exhaust usually smells different from petrol.

[rlubikey]

20 hours ago, JohnD said:

Consider: the ceramic tiles on the Space Shuttle, that protected it from a similar thermal gradient as in and out of the manifold.needed to be six inches thick.

John, have you seen the video ... I think it was Allen Millyard, where he uses gas fire ceramic briquettes, cut and shaped to go around his exhaust to add insulation? Now which of his project videos was that on???

Cheers, Richard

[JohnD]

No, Richard, I haven't!   If anyone can point to the right place, I'll be grateful - otherwise an awful lot of videos to look through!

Interesting guy, excellent workman, but a biker!

John

[Ian Foster]

Gav

Here's a photo of the manifold side of the engine. Not very clear I'm afraid as exhaust manifold is partially obscured by the heat shield.

The finish is a very light silver as you can see.

(I also fettled the manifold to port match the head, whilst it was off the car)

Ian

[rlubikey]

I've juuuuust this second found it John. Millyard Viper 8 Litre V10 Motorcycle - Part 1 starting at 3:37.

Richard

PS: Now if only I could remember how to embed Youtube ...

[trigolf]

1 hour ago, Ian Foster said:

Gav

Here's a photo of the manifold side of the engine. Not very clear I'm afraid as exhaust manifold is partially obscured by the heat shield.

The finish is a very light silver as you can see.

(I also fettled the manifold to port match the head, whilst it was off the car)

Ian

Thanks for the pic Ian. I dropped off the manifold with QSE yesterday. I opted for the same finish.

Gav

[Ian Foster]

Good decision. I'm sure you won't be disappointed.

Ian