1986 240 DL Engine sound like a VW now

I think it is two things - a failing muffler (or other exhaust parts) and need of a tune up. The exhaust system is easy to check - listen under the car for a puttering sound, or roar if it is bad enough.

Mike

"Michael Pardee" wrote in news:VZGdnZYG29YbYV snipped-for-privacy@sedona.net:

Thanks

Very hard to tell--could be some water in the gas or a very small exhaust system leak, could be something else....

"Steve n Holly" wrote in news: snipped-for-privacy@comcast.com:

Well, today started the car for the first time today and drove it about 1 mile from my house and all of a sudden I heard a loud pop from under the hood, turns out that one of the spark plugs popped out. It was hanging there, so i pulled it out and it was like melted at the thread. I talked to a guy today and he said it could be oil pressure is too high. So, I'm gonna replace all spark plugs and get an oil change. Hopefully that will do for now.

A damaged spark plug thread that leaks under combustion can be noisey in a way that I suppose could be described as VW-like.

I don't like to dampen your spirits, but I'd be seriously interested to know how oil pressure could affect the spark plug thread. It may be that the guy you talked too had his mind on other things.

What I'm guessing is - the 'melted thread' effect is caused by the thread being stripped out of the head, which has been cause by a careless mechanic overtightening the plug. Although to get to the stage where the plug just pops out means this has been done very carelessly indeed.

It can probably be repaired with an insert of some sort (eg Helicoil), but this will almost certainly require the head to be removed. I expect you will find out when you try to put a new plug in the hole - you won't be able to get it to tighten.

Try to avoid driving the car with a missing spark plug. You will not only make a mess of things under the bonnet, but you may damage the crankshaft, which will have an unrestrained load on one cylinder.

There's no way oil pressure has anything to do with the spark plug, if that's what the mechanic honestly thinks then you need to find a new mechanic.

If the plug is actually melted then that cylinder may have been running very lean and will probably have burned valves. As another poster said though it may just be stripped out. Sometimes with care you can get a plug to thread in and tighten if the problem was caused by someone crossthreading it. Otherwise you'll have to helicoil it or (recommended) replace the head with a good one from a junkyard.

It's more likely the vehicle not firing on all cyclinders. The "sounds like a VW" is the giveaway symptom.

Well he said one of the spark plugs fell out, I would say it's pretty safe to assume it's not firing on that cylinder at least.

When this happened to my Lotus with a Renault 16 engine, I removed the head and took it to a cylinder head shop in Phoenix I later came to trust (Arizona Cylinder Head, for the locals). They recognized it as a Renault head when I carried it in, and told me it could be helicoiled. They also said aluminum heads don't have to be removed to be helicoiled - the shavings blow out through the exhaust. Of course, that was before catalytics. Another method I've heard of is to run the piston to BDC (beginning of the compression stroke) and fill the cylinder with shaving cream. Tap the hole and pull the engine through the compression stroke to push the shaving cream out the spark plug hole, carrying the debris with it. I can't vouch for either method myself, but it might be worth the research. DIY tap and coil kits are widely available in auto parts stores.

BTW, stripped spark plug threads are common in aluminum heads. Using antiseize on the plug threads and a torque wrench to tighten them are your best insurance against more of the same.

Mike

Heh! I've not heard of this use for shaving cream before. It sounds plausible. The method I heard was to pack the flutes of the tap with grease to hold the swarf, but I wasn't convinced it would work.

They are, but IME cost more than a single insert at a workshop. If you have to do this more than once, and want to do it yourself it may be worth the investment.

I reckon that spark plugs are the most over tightened item on the car. They are the thing that many people will have a go at changing themselves, and thinking they are doing the right thing, swing on the wrench like it was a wheel nut, over stressing the threads. A plug change or two later, and it mysteriously won't tighten properly. They would have got away with this in an iron head, but not an ally one. You really don't need to apply much force to seat a plug properly.

I've heard of the grease method too, but the shaving cream one is new to me.

The guy that used to be a tenant in my neighbour's basement was out changing the spark plugs and air filter in his Sentra. A couple of hours later, I heard an anguished cry - "Why does this damn car run worse now that I've changed the air filter and spark plugs?!" So, being a nice guy, I walked over and asked (while listening to a car running on

3 cylinders), "Did you gap the plugs?" "Gap the plugs - what's that?" Sure enough, one had been dropped, there was no gap at all! Some people actually hurt their car by trying to do maintenance - and even worse, "professional" mechanics are often no better.

When I started using a torque wrench on the spark plugs I was amazed how little torque 25 ft-lbs is. The threads on a spark plug make it look large and stout, but it gets torqued down like a small screw.

Mike

SIEGE wrote in news:Xns95C21AF8BBB8Adjsiegecomcastnet@204.127.199.17:

Replaced all spark plugs today. Drove it 10 miles roundtrip, back to normal. Thanks.

My guess - cracked exhaust manifold. The performance problems are because the O2 sensor is near the cat, downline from the crack/hole.

Yep. Finger-tight and then something like 1/16th-1/8th a turn is all you need. I'm amazed they don't use a bayonet type setup instead.

Me? I buy my plugs pre-gapped.(NGK and a few others come this way) - double-check and install.

SIEGE wrote in news:Xns95C89527DA3CEdjsiegecomcastnet@216.148.227.77:

Well yesterday the same spark plug popped out again. It's definetly stripped. I put some antiseize on a new spark plug in, and i was able to drive home. But now I'm not so shure about driving around. How reliable is the antiseize method.

Antiseize is to PREVENT stripping the threads. Your threads are already gone--what is done in this sort of case is that a slightly larger hole is cut into the metal of the head and a insert threads into the newly enlarged hole. The plug threads into the insert.

This is a job for a skilled person--I have seen it done when I was working in various garages, however I would not try it myself--YMMV!

I had a feeling you were being over optimistic. But worth a try.

The anti-seize paste is not a way of dealing with a stripped thread; it just makes it easy the undo something that may be subject to seizing up. Some people advocate putting it on sparkplugs before they fit them, because a seized plug can be a major problem to get out.

I'm afaird the only answer to a stripped thread is an insert. Helicoil is the most common type, and most automotive workshops will be able to do it for you.