400SE downpipes (manifolds)?

[ElvisWedgely]

I took my 400SE to the local exhaust centre for a leak test as I can sometimes smell fumes in traffic. Previously I had new olives replaced at where the manifold meets the exhaust but this hasn't cured the problem. At the exhaust centre they blocked the exhaust with a cloth and checked the entire exhaust which seems fine. At the manifold end however we could hear a leak and the engine made no attempt to stall. So, it seems there is a leak somewhere around the passenger side manifold. It could of course be the manifold gasket but this seems unlikely as The previous owner replaced it. I am now thinking there must be crack or a hole somewhere. It might be easier for me to have the manifolds replaced with new gaskets rather than mess about welding and speculating. What I want to know is this. Where can I buy the manifolds from? how much are they and what is involved in replacing?. My classic car garage will be doing the job but I need some briefing so as I know what I am talking about when I speak to them. So gentlemen, expert mechanics and Wedge wizards. Any help or advice would be welcome to solve my dilemma. Thanks in advance.

Tony. TCB.

[Wedg1e]

I wouldn't count on it not blowing from the manifold gaskets just because they've been replaced. There are some crap quality ones out there that don't stand up to a V8 very well.
Also the 3/8" UNC manifold bolts are VERY prone to stripping the head threads, especially when people try to cure a blowing gasket by just tightening the bolts further
All the welded joints are pretty easy to get at so the garage should be able to pinpoint it better than it sounds like they have, which also makes me think it's a gasket as it's hard to get near when the pipes are hot.
On the other hand if it needs a new manifold, can I have the old one? Mine have more patches than a Microsoft product.
There is a guy on Ebay who sells a kit of parts from which you can fabricate your own manifold, of course it'd be easier with the engine out of the car but maybe worth a punt for under £200 if you can weld and have the kit?

[pwd95]

Try the gaskets first. Get the large bore ones like these........
http://www.ebay.co.uk/itm/ROVER-V8-BIG-BORE-EXHAUS...

& double them up, so get two sets.

[ElvisWedgely]

Ok. I will get them to check the manifolds for leaks and if they say it's ok, I will tell them to just change the manifold gaskets. Looking at the manifolds, visually they look good to me but I'll wait and see what they say. Are the 400SE manifolds the same as the Rover V8 or not? If they are Rover it should be easier to get hold of should I need to have them changed.

Tony. TCB.

[jon haines]

I had a crack in one of my manifolds which i had welded up for £25 but i had to have my faces skimmed which was a far bigger issue but still is a reasonable cost thing if you can find someone to do it. £40. compared to cost of replacement its cheap so it depends on the overall condition of the manifolds as to weather it's worth it.

[pwd95]

The manifolds are bespoke. Tight fit too. I think several of the big TVR suppliers do them off the shelf. Worth ringing around.

[RustyNailer]

ACT do them I am sure.

Rob

[Jack Valiant]

Old school test .... run engine and pass down the branches of the manifold a piece of tissue and look for movement this will tell you where it might be. Also is the smell really exhaust? Could it be some fuel leaking from the fuel lines or returns near the exhaust and coming up through the gear or handbrake gators. Got to get the car up in the air and spend some time to find it, thought i had a similar problem years ago and it was some fuel mixing with the heat of the exhaust.

Chris

[grahamw48]

RT racing supply them....standard or stainless.

Double the price for stainless.

[Solitude]

Removed my pass side manifold to have a hole welded (no welder will do it in situ)

Discovered (raised part of the ports) were "blow damaged". Chap built them up with weld then drag filed before i put a set of (bigger bore as Wyn said) gaskets on.

Bd of a job as the engine mount had to be removed to get the manifold off.
Bolts came off and new set went back with no problems, but it was a bugger to seperate branch from ongoing exhaust, and real tricky setting the gaskets and getting it all back together again.
Six months later and the hole is back !!

I would love a stainless set but cant stretch to it.

[ElvisWedgely]

If I have to have the manifolds removed for welding I might as well fit new ones, as the removal labour charges won't be cheap if the welding don't last long. I suppose I could say the same for manifold gasket replacement, as I guess the manifolds still have to be moved. If you do the job yourself, then it's ok, because if things go wrong you could always re do the job another day. I have to work this out well, otherwise it could turn out to be an expensive project. I am willing to hear from anyone who has had, or has done this job before.

Tony. TCB.

[mrzigazaga]

Hi Tony..Here are the ACT ones..or you could always give pipecraft a tinkle..Ziga

ACT:
http://www.actproducts.co.uk/shop/index.php?main_p...

Pipecraft:
http://www.google.co.uk/url?sa=t&rct=j&q=p...

[grahamw48]

....and RTracing (Richard Thorpe).

http://www.rtracing.co.uk/content/tvr-sports-perfo...

[Wedg1e]

ElvisWedgely said:

If I have to have the manifolds removed for welding I might as well fit new ones, as the removal labour charges won't be cheap if the welding don't last long. I suppose I could say the same for manifold gasket replacement, as I guess the manifolds still have to be moved. If you do the job yourself, then it's ok, because if things go wrong you could always re do the job another day. I have to work this out well, otherwise it could turn out to be an expensive project. I am willing to hear from anyone who has had, or has done this job before.

Tony. TCB.

If you were a couple of hundred miles further north I'd offer to help

In principle it's an easy enough job; some of the manifold bolts are accessed more easily through the wheelarch (with the wheel off).
Might be easier with the engine mount out of the way but I'm sure that last time I dropped my n/s manifold I didn't need to (stainless-to-mild joint weld had cracked).

You can get a one-piece gasket with all four ports joined by a link that is easier to fit... but whilst it may be OK on a standard 3.5, it won't last 5 minutes on a large-capacity RV8. You NEED to use the four separate gaskets (some people say double them up as well, I've never bothered and in some ways it seems counter-intuitive since if the clamping pressure isn't equal with one layer, it isn't going to seal two layers any better). One slight issue is that juggling a manifold, 4 gaskets and 8 bolts can be... entertaining

Sight along the mating face of the manifold (or use a straight-edge or, better still, surface plate and marking blue) to make sure it's flat; as said earlier any cavities caused by escaping gases need to be welded and trued-up. In any case have a good look at the mating face of the head itself, aluminium melts easier than steel does so blow-by can cause damage to the head that isn't matched on the manifold. Minor pits will fill with exhaust sealant but anything more serious.... well, you know where that will lead.

Check all the manifold bolts for aluminium swarf stuck in the threads; it's a clue that the head threads are stripping (or already stripped!). There isn't room to get a drill in a Wedge engine bay to open out for Helicoils - you might manage the forward ones with a right-angle drill but I doubt you'd get at the rear threads - so it then becomes a head-off or engine-out job... or you could bodge a longer bolt in and hope for the best, but IME stripped threads are one of the main causes of gasket blow-by.

So lots of doom and gloom there and of course it may not be the gaskets, but if it's a cracked manifold it'll need to come off anyway... and it's only money, afer all

[hallsie]

Solitude said:

My Chimp boyfriend removed my pass side manifold to have a hole welded (no welder will do it in situ)

My chimp boyfriend lover Discovered (raised part of the ports) were "blow damaged". My chimp man love god built them up with weld then drag filed before he lovingly put a set of (bigger bore as Wyn said) gaskets on.

Bd of a job as the engine mount had to be removed by my chimp boy sweetheart to get the manifold off.
Bolts came off and new set went back with no problems, but chimp boy was a buggering me to seperate branch from ongoing exhaust, and real tricky setting the gaskets and getting it all back together again.
Six months later and the hole is back, but my Monkey lover boy will plug it for me !!

I would love a stainless set but my lover chimp man is not big enough to stretch me to it.

EFA,



Stu

[wedgemaniac456]

Usually if there is a leak around the exhaust manifold gasket you will here a tapping sound this happened to my 400se.Replaced the gasket and it hasnt returned.Lots of grazed knuckles though:

[grahamw48]

This is true, and if there are several, suitably positioned, you may hear a fair rendition of the 12 days of Christmas.