Hi
I saw a post the other day about a shop that didn't replace the exhaust manifold gasket properly or something. the owner began to hear a ticking or popping noise after the work was done and a lack of power??? Can't find the post again but anyway....

.I just had the dealer who sold me my 98 disco replace one of the catalytic converters (it was rattling). This was part of the deal whenI purchased the car.Now I hear a ticking sound - like cards in your bike spokes- when I excelerate. checked under the hood and under the car. There is a deffinite exhaust leak somewhere around the passenger side exhaust manifold . even a small backfire on excelleration. These sounds weren't there before the work was done. Maybe its my imagination but I swear the power is decreased too. I noticed the newcatalytic converter is different (smaller) that the original one on the other side too. I can't tell if they cut the exaust system to put in the new converter while stillconnected to theengine, or took the system lose from the engine before cutting the pipe. I was wondering if they might have pulled the manifolds and put the gasket on wrong. this accounting for the loss in power.
I'm frustrated and don't want to drive all the way back (180 miles round trip) to have them do it right. Am I gonna have to take it to my local muffler shop and eat the repiar cost or is there something I can do myself. I hate working on exhaust systems!!
What say ye experts?
thanks

 

I would go to the local muffler shop and have them look it over and see if it is something that the dealer did. And if so I would take it back to them. Unless the cost of the repair is less than the cost of gas round trip.
And since you just bought it, you are using premium gas right?

 

I don't know how they could have put the gasket in wrong and you not noticing it when you left. If it didn't fit/seat properly, you would have noticed it right away. Now, usually a few days after putting non new gaskets (manifold to head) they can stand to be retorqued. Soooo, if it were me, I'd put a wrench on the Exh manifold bolts and see if any feel loose and tighten as required.

As for the catalytic converter size goes, whoever currently supplies the dealer (or Rover) might be different than who used to supply them. In fact, it's a good bet it is a different supplier. Also designs have changed allowing C/C's to become smaller. That might account for the smaller physical size. The new C/C's are less restrictive than the old ones.

As for the Power thing, are you using Premium, or accidentally put in a tank of regular?

You've got the right idea going to a local muffler shop and let them have a look. Maybe the C/C is restrictive. They can probably pull out a O2 sensor and put in a pressure probe and see if it's higher pressure on the one side.

 

That was me ,with the gasket wrongly installed. Thing is, that if you take the gaskets and turn them around, the bolt holes will still get in line with each other, but the ports will be half blocked. You put them on the good side, and of course, the bolt holes are perfectly in line, and the ports are not obstructed by the gaskets. Not sure if my description is clear, but I saw it and it's basically unbelievable. I guess that it's one of those things that you have to see to understand.

So........When the gaskets are put on the wrong side, since the the ports are some 30% blocked by the said gasket, the exhaust hits it and since they are made of 3 thin layer of metal, they emit a ticking sound.

Doesn't mean that all ticking sounds are related to this. I'd start with the y-pipe gaskets.

 

Thanks guys for the input.
by the way, I did hear the leak as I drove away from the dealer but at that point they had had my disco for a week and a half and i just needed to drive home as it was late in the day and I had 90 miles to drive.
I took the rig to my local muffler guy today. He thinks its leaking at the passenger side manifold gasket. You can hear a leak there for sure butjust where is a bit hard to tell with a quick look. He also said since a disco 'Y' pipe-the one with both cat. converters- is soooo expensive that the shop that did the repair was justified in just cutting out the bad converter and welding in a new one as long as it was for the proper engine output. He said he has done the same thing.
I asked him if he thought the other shop would have taken the manifold lose to do the job. he said he would have just cut the bad converter section out in place- that is, cut the pipe while still on the car.
I don't see how that could have caused the exaust manifold to leak, but it is.Or maybe the manifold itself cracked from the sawsall vibration??The leak is a noticable exaust sound when idling , but when Idrive it , it becomes a strong tic,tic tic,when i put a load on it,like cards in bike spokes like i said before. That's what made me remember the story of the manifold gaskets being put in wrong.If they didn't take off the manifold ,then the gaskets haven't been messed with.
I still can't tell whether I'm imagining the power loss or not.
Yes I'm running premium gas.
The local muffler guy is checking into parts on Monday.

 

It's also possible that the leak existed prior to the work being done but that the old cat had less back pressure due to damaged baffles. It would make sense in that case that the new cat's causing enough back pressure for the leak to become apparent.

Dave

 

After you get your exhaust leak fixed them send some time and see what killed the old cat, they just don't roll over and die, they fail, then rattle because of contamination be it oil, coolant or excess fuel caused bu bad plugs, wires or dirty/failing injectors.
Bottom line it will come back and take out your new cat if not corrected.

 

thanks again for more input
Yes I'm aware that c/c's don't just die. i'm concerned about what caused the old one to fail. diagnosing that should be another thrilling episode in "the life of this disco and its owner".
The theory of the leak being more noticable now because of more backpressure due to a new cat... That's a very good point, except that the bad cat was on the drivers side and the leak/ noise is on the passenger side.
I'm wondering what the muffler guy will actually find when he gets into this. I hope not much because I'm not looking forward to a big bill after just buying the rig. Also if the bill and damage is small enough i might have a chance of getting restitution from the dealer or the shop that changed the c/c.
I can dream can't I?

 

Speaking of CC's. Any reasonable way to put in a bypass for them? I'll be traveling and there's a chance that leaded gas will be the only thing available in places.

 

In case anyone cares.... I just got my disco back from the local muffler guy. He replaced the gaskets on both sides where theY pipe connects to the manifolds.The cards in the spokes/engine knocksound is gone! Its a miracle!! This noise was so much like a serious internal engine sound and yet It only cost me 78 bucks labor and materials and I didn't even have to get my hands dirty. ( I usually do that sort ofrepair myself but geeze! I just bought the car). Aparently when the last muffler shop welded in the replacement cat./conv. they had to drop the pipe down to weld all the way around the top.When they put the pipe back on that was when the gasket failed causing the alarming noise. Amazing how that 1st shop sent it out without fixing their mistake! Jerks [:@]I guess i eat this one
For your info- the failed gasket looks almost perfect. Hard to believe such a small leak could make such a big noise!