Exhaust Failure

[Guest Duncan Venn]

When I arrived home the other day, I noticed that the exhaust on my Exmo had come apart. I'd been dimly aware that the volume had increased, but I use an ipod and noise-cancelling earplugs (at least they seem to work!), and certainly hadn't realised that it had come apart.

 

What seems to have happened is the 4-into-1 pipe has moved forward in some way: it used to sit in the middle of the hole where it exits the engine bay, but is now hard over to the right if you look at it from the side and points outward a few more degrees than it used to. This has pulled the 4-into-1 out of the pipe going to the silencer, causing it to come apart.

 

My immediate thought was that something catastrophic had occurred under the bonnet, but on giving it a quick inspection, the engine and gearbox mountings remain secure and have not moved, and the 4-into-1 remains firmly attached to the head. There are no obvious signs of any other movement or damage, the car continues to run fine. There is no play in the 4-into-1, which has so far done its job without incident for 20K miles so I'm a bit mystified.

 

I've got exhaust wrap round the 4-into-1, which I'll remove this weekend to see if it reveals anything and I'll do a more in-depth inspection, but beyond extending the existing silencer pipe and adding a bit more of a bend, I'm not sure what else to do.

 

Anybody seen something like this before?

 

Duncan

[Guest peter2b2002]

no

peter2b

[Foz]

Mine tends to come a tad loose on this joint & needs to be tightened once or twice a year, but it's never come anywhere near to parting company.

Steve

[Guest mower man]

When I arrived home the other day, I noticed that the exhaust on my Exmo had come apart. I'd been dimly aware that the volume had increased, but I use an ipod and noise-cancelling earplugs (at least they seem to work!), and certainly hadn't realised that it had come apart.

 

What seems to have happened is the 4-into-1 pipe has moved forward in some way: it used to sit in the middle of the hole where it exits the engine bay, but is now hard over to the right if you look at it from the side and points outward a few more degrees than it used to. This has pulled the 4-into-1 out of the pipe going to the silencer, causing it to come apart.

 

My immediate thought was that something catastrophic had occurred under the bonnet, but on giving it a quick inspection, the engine and gearbox mountings remain secure and have not moved, and the 4-into-1 remains firmly attached to the head. There are no obvious signs of any other movement or damage, the car continues to run fine. There is no play in the 4-into-1, which has so far done its job without incident for 20K miles so I'm a bit mystified.

 

I've got exhaust wrap round the 4-into-1, which I'll remove this weekend to see if it reveals anything and I'll do a more in-depth inspection, but beyond extending the existing silencer pipe and adding a bit more of a bend, I'm not sure what else to do.

 

Anybody seen something like this before?

 

Duncan

Yes twice 1st time 3/4 years ago ,4/2/1 shattered at 2 to 1 joint ,weld repaired ,ran up untill last week end volume increased on way home from open day ,pulled manifold off same place cracked around weld repair !.Fortunatly have a new unused manifold ,waiting for new wrap and straps . I think the mod I did after the first prob has helped stop an earlier failure , I cut out a section of front pipe and fitted a flexi pipe instead this alows the engine to move without stressing the front pipe also the silencer has 2 mounts. Cause? vibs from an unbalanced eng ! any one got thoughts ? mower man

[fry61]

Only got one mounting point at rear of silencer (2 bobbins close together) manifold is solid up to silencer front end with just one S/Steel clamp,all O.K so far; 4000 miles.

My take on it is that the engine can move the manifold/silencer around the rear rubber mounts so no stresses on the pipe run.

[Guest Duncan Venn]

Thanks very much, very helpful. I'll take the 4-into-1 off tomorrow and see if I have the same problem. I'm going to see a bloke with a welder tomorrow anyway, so I'll get him to deal with it if that is the problem

 

Duncan

[Guest mower man]

Number of mounts on my car [2] is because of the 27"x 6" silencer ,probably the orig can would be ok .The flexi used is a s/s braided on from a modern were its used to stop front pipe breakages it is 10" long. After inspecting the break ithink it was probablly old age it was 15 years +old mower man

[Guest Duncan Venn]

I've now taken my exhaust manifold off, and it is a bit knackered. There is pretty catastrophic damage to the 2-into-1 connector taking the output from cylinders 2 & 3, It is cracked around the bead where it is welded onto the single pipe coming out of the connector and there was a large tear up the middle of the connector on both sides. On tapping around this to get rid of the crud, more metal gave way to give the hole in the pictures. There are also small cracks in the 2-into-1 connector for cylinders 1 & 4.

 

I discussed it with a friend who is a qualified engineer, who reckons that it is the material that has failed, and the metal in the connectors certainly seems to have worn more than the pipes themselves, which all look in good condition. I suspect that this isn't helped by the fact that I've had a small additional silencer on the pipe, and with only 2 attachment points (the head and the back end of the main silencer), these connectors have had to bear quite a lot of weight and vibration

 

It doesn't look like a straightforward job to replace the connectors, so I'm in the market for a new manifold if anyone's got one spare! I've put my request in the wanted section

 

full manifold:

hole in 2&3 connector:

cracks in 1&4 connector:

 

Duncan

[Guest mower man]

Hi the damage on your manifold is in virtualy the same places as mine but far more comprehensive fortunatly I had a manifold to hand which I aquired from here a good while ago ,not knowing how long my repaired one would last ,it actually did 4 years or so. I would advise another mount if you have any thing heavier than the std RH can ,its along way with no support ,try and get a little compression on the mounting bobbins as they seem to last longer if not in shear or tension in fact I 've not had one break in a good while, and the silencer I have is 25"long and 6" diam and repacable so its quite heavy .Replacements are some times a bit diffcult source and custom made can be very expensive , I had lot of quotes of 3to 500 pounds when I searched some wanting the car for 3 weeks to ensure correct fitting hope you find a suitable replacement .BTW I didn't try GBS stupid really they are only 15 mins away from me------ regards mower man

[Guest mower man]

As my last post stewart ,not really studied zero system but as you say with a cat and a silencer ther is a lot of weight on one mount the flexi I have used is approx 10" long , I removed a peice of front pipe to suit and made a new mount at the front of the silencer bolted to the tub [ it's a circa 96 mono car ] .the flexi's are available in several lengths i.e. 4 ,6 ,8 ,10 and 14 ",I paid around £16 for the 10",3 nice s/s clips finish it of nicely -- regards mower man

[Guest Duncan Venn]

I've now been to a specialist manifold builder who took one look at it and asked if it had been covered with exhaust tape. He said that it is quite common and is the metal cooking off because the heat can't dissipate. Worth knowing about for the future. He said he'd rebuild the centre section (all 3 joins) for £150.

 

Duncan