Damaged SOMETHING with backfiring ...

Is the engine running smoothly? maybe a spark plug is not firing or the wires are crossed and not in the proper firing order.

Have you removed the catalytic >Is the engine running smoothly?

JRE

Backfired and now low power sure sounds like a blocked exhaust, as Jim said.

it's 1,3,4,2 just replaced the distrib. in my 85.

md

Jim, WATER-cooled and not AIR-cooled! I see what you are more familar with! ;-) I try to remember when redoing plug wires, but there are times when.......... lol

Exciting new data!:

Well, I pulled each plug wire with the engine running, and found that the noise comes from cylinder #2. The noise occurrs with each spark (I checked with a timing gun). Where does this leave me? Sounds expensive.

Note: I should have said "inline 4," and noted that some of them have been VW's. I have also infrequently worked on horizontally opposed 4's but don't recall their firing orders and whether they differ.

JRE

When you pulled number 2 plug wire, what changed? The "loud clanging noise" stopped, got louder, or what?

The noise stopped entirely.

Also, I can feel some pulsing air when I put my hand around the back side of the engine, so maybe this noise is some exhaust leak? But then why would I have a loss of power and why would it be isolated to #2 piston? Hmmmmm.....

Well there are also V-4s in some Saabs and then there are engines that are

It is all good JRE and I think you are correct with the firing order of the VW I4 cyl engines! ;-) Next someone will say that the engines can be inline or transverse. lol

later, dave (>> While I've no experience with this particular engine, I doubt that's the

Check valve clearance. Still check catalytic converter. Always remember Jim can't get the timing order correct unless he opens his Bentley. Oh, remember that problems are not neccessarily binary. It is either this or not. It can be multiple things. Maybe cylinder 2 is the only powerful cylinder so it makes the most noise. That is just a silly comment. I have had exhaust come out everywhere when the converter gets clogged. Everywhere including the tailpipe. Flanges, manifolds, anywhere it can escape. Some of the noises that are made by exhaust leaks are really bizzare. Remember that the gaskets are metal sometimes laminated over an asbestos like core. That means you have reeds like an oboe or a saxaphone. You know how bad those instruments can sound. Exhaust wizzing by those reeds makes some horrendous noises.

Well that jogged some of the ole gray matter.

Check the brake booster and its line. I seem to remember someone else with a problem similar to the OP's and their booster was bad creating a large vacuum leak and nasty running problems.

But now I have forgotten which car that we are talking about! lol '81 Rabbit Conv? I need to have that info put in the Subject line! ;-)

Well, I got up under the car with the engine running. There is definitely a leak/hole around the exhaust manifold between the #1 and #2 "tubes". This probably explains all the noise (right?), and since it coincided with the loss of power, it should explain that as well (right?). So this is where I'm going to begin.... Now the question is, is this job doable for a non mechanic? All the bolts are heavily rusted and I can already see myself crying under the car with rust dust in my eyes.

No, it does not explain the loss of power. The destroyed catalytic converter is the loss of power. The leaky gaskets from 1 and 2 are signs. Has your stomach ever rumbled? It is usually a sign that you need some food. It is not a sign that you need to clean your fingernails. Exhaust leaking out of places it is not supposed to exit has two meanings. One is bad gaskets. Two is restriction in exhaust sytem. No restriction in exhaust system means there is a lower chance of you noticing leaks at manifold.

It is not rocket science to inspect your converter. It requires a contortionist though. Remove 6 bolts and inspect both ends. Six point sockets and 6 sided box end wrenches work better than 12 point equipment. Since you have the converter off you can proceed to remove the manifold. That path is full of land mines. Nuts that are a 1/2 mm corroded. Rounded off nuts. Get out your Silikroil and start spraying those nuts for the next two days. Or if you are good with a torch you might get them loose with a torch. I usually have at least a handfull of fresh nuts and maybe even a few fresh studs if I have rotten luck.

I would really focus on inspecting the converter first.

I would also get a good pair of saftey goggles. Rust in the eyes can be a trip to the doctor.

I'm a non-mechanic and I did my mk2's manifold and a complete exhaust replacement but I did it over several weekends, working no more than 2 hours at a time. I didn't want to stress myself out to get it all done in one weekend.

My advice is to put the car up on ramps (or some other VERY stable device) first because you might need to work from both above and below the car.

The day before (with the engine cool), soak all nuts/bolts with PB Blaster penetrating lubricant. This helped. However I did snap one stud off (I believe it was defective or cracked already because it did't take much effort on my part...it's not like I forced it. Fortunately it broke off with plenty sticking out and a friend came over and used a stud extractor and had it out in seconds. All the other studs stayed in the car (only the nuts came off) so I didn't bother replacing them with new ones on installation...I kept the old ones in there and just used new nuts although if u have a stud extractor i guess you can extract them all and replace them all.

Also now would be the time to think about any type of exhaust upgrade anyway. I'm not familiar with what the mk1s (was this a mk1?) have stock vs. aftermarket but might want to think about things like a dual manifold swap if you have single now, etc.

Okay. Thanks Jim (and others)!!! I'll do that first. Should I test the car with the converter off to see if the power has returned, or is that a bad idea?

It'll be loud as hell unless you have a test pipe, but it's worth a shot.

nate