Inlet / Exhaust Manifold Stud confusion

[Mighty_Quinn]

Hi All,

I've been reading all of the posts about the no.1 manifold stud as it seems that my symptoms point to this problem, but with all the seperate discussions I am now really confused so hoped someone could double check my working out before I go off and order lots of parts.

My bongo drives fine, but when it hits about 2,500rpm under load while driving I get a very loud and pronounced squealing noise which remains constant in pitch and volume until I back off the accelerator and drop below 2,500 revs where it goes away.

My garage aren't that experienced with bongos, but they have been doing servicing and an overheating problem as well as the front fan blowers rheostat issue - over the past 4 years. Now they seem to think that they have tracked the sound back to the INTAKE manifold on the elbow between the intercooler and the intake, and so they suggest that I replace the two gaskets to fix the problem.

So I checked on here at what more experienced bongo owners thought and it appears that there was a lot of scorn for a garage that suggested the intake gasket could even make this sort of noise and that the problem was either the EXHAUST manifold or the no.1 manifold stud shearing off.

Now my garage say they checked the exhaust manifold and are almost certain there is nothing wrong with it, so don't think there is any point in me ordering that part. They are sure it's on the INTAKE side ... though they did look at me a little blankly when I mentioned the exhaust manifold stud.

I noticed people describing the manifold stud sound as a chirruping or grasshopper, mine is a definite squeal - and also it is only when driving under load - wouldn't an exhaust manifold be constant? Somone also said on one thread that a leaking INTAKE gasket would be a ticking noise not a squeal - so I'm very confused now!

Is there any way I can check for this stud problem myself? Should I just order the replacement studs as well as intake gaskets? Oh and my exhaust back box just dropped off and there's corrosion on the centre section so I'm having to get both sections on order as well (could this be related to the squealing noise?)

Thanks all

[Mighty_Quinn]

I've had a look under the passenger seat - wide shot of where i'm looking which is where I think the exhaust attaches. close up shows what looks to me like a bolt with a sheared head, there is another bolt above that with a head on it but I couldn't get my phone in the gap(!)

[francophile1947]

I reckon you've found your screeching noise The noise from the stud varies considerably, but only happens under acceleration.

[dandywarhol]

Give your "mechanic" a pair of specs and never come back on here doubting us

[haydn callow]

I think that is the wrong place you are looking...that looks like the end of a bolt to me.
This is where mine is..."I think"
Dandy....Help.

[haydn callow]

don't seem able to orentate that 2nd photo in the first post...or have you removed the heat shield ??

[dandywarhol]

Mine was broken where you pointed out on yours Haydn.

[haydn callow]

Thats not the same bolt as in Mighty_Quin's photi is it ?? so perhaps his garage are not mistaken....we need a photo of his No 1 stud

[westonwarrior]

My microscope and eagle eye suspects the picture is of this area



not an inlet manifold stud

[dandywarhol]

You're right weston - still, it looks like a sheared bolt/stud on the exhaust side of the turbo

[haydn callow]

Thats not normal if thats the case.

[Mighty_Quinn]

Hi All,

Thanks for the rapid replies. Westonwarrior is exactly right with the location of my picture. So it looks like I might well have a sheared bolt on the ' exhaust side of the turbo' (thanks dandy) as well as this...

I took off my heatshield and had a good look round and spotted this as well - looks like a missing stud at the bottom left of the exhaust manifold. (had to move the dipstick out of the way to take the picture)



different view with a torch on it

This is the top where I was originally looking for a number one stud

and that looks fine to me - although there does appear to be a little sooting to the top left of the exhaust manifold which suggests that there might well be some exhaust gasses escaping there (?)

This picture shows the location of the two gaskets that my mechanic thinks are the problem - under the drivers seat to the front of the engine


advice much appreciated before I start ordering a shed load of parts

cheers

[haydn callow]

I would get that No 1 stud fixed (the one with the torch on)....easy job...and see if it sorts it....Thats the one in my photo above.......that causes a Belt slipping screech !!

The job can be done without any dismantleing.....just swing the alternator out of the way......use a carbide drill to drill out any stud left in then helicoil and a bit of replacement stud.....couple of hours work.

[dandywarhol]

So we're back to the original diagnosis, the main problem IMO is the missing/broken stud.

There might be black gunge around the inlet side - if the gaskets being replaced there best to blank off the small pipe altogether - that'll lessen some of the exhaust smoke. Plenty bumf about it under "EGR" in "search"

[missfixit70]

I'd ignore the inlet side for now, but this may be of interest re the egr as Dandy said when you get around to it- http://www.igmaynard.co.uk/bongo/forum/ ... 43&t=14463 .
You might get lucky with a stud extractor on the exhaust manifold stud, would save having to helicoil, just take it real easy.