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On the last 10 miles back from Carlisle my tub developed a metal to metal annoying noise upon accelerating and putting a load on the engine-in the driveway it sounds normal even when I rev it up.The engine is a mexicrate  that we built up to 1914 almost 5 years ago and now has 16,000 miles on it. It is a nonstrocker with stock heads and a mild cam (engle 100 or 110), dual weber idf 40s,electronic ignition, 4 quart sump, kennedy 1700 clutch and extractor exhaust with a phat boy muffler.  I also installed a crankcase breather system that vents thru the valve covers to a box on the firewall. .I didn't think the noise was coming from the engine but I did the following: 1. checked the valves (cold) -all the clearances were at .006 and nothing appeared loose or bent. 2. took the fan belt off and checked the fan and alternator for looseness or end play-both OK and nothing stuck in the fan. 3.I took off  the muffler to check for a loose baffle-nothing there. No leaks  or looseness in the exhaust system .4. I checked all the tin to see if any was loose-all tight.5. I even changed the fuel pump and push rod to make sure that wasn't causing the noise. I was pushing the speed because we made the 200miles back from Carlisle in just over 3 hours.

I then called Kirk at Vintage. They built the car in 2006. He thought that there might be a broken or loose trans. mount.

Out of frustration I drove the car yesterday morning to Freccia Brothers Shop in Greenwich ,Conn-an old and well respected aircooled vw shop so they could put it on a lift. They called me today and so far can't find the source of the noise. Trans. mounts are OK. They drove the car and thought it lacked power so they pulled the plugs which I had changed about 1000 miles ago-one was fine,one was oily and two looked like there wasn't much combustion. They did a compression test -3 cylinders were normal at 135-150#but #2 read 250# ! All three mechanics have  never seen this before. I asked if it could be excessive carbon buildup on the piston head or the valves-they said maybe or a loose head stud or a crack. So far they don't want to pull the engine and are looking for solutions. These guys have experience, and know their stuff. They gave ma a lot of time today on the phone.

Does anyone have any ideas? 

Thanks,Joel

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Slightly Loose rear wheel hub nut?

I don't know WHAT to tell you about the differing compression figures.  A carboned-up plug is either running really rich or has bad spark (or is just a bad plug....It happens).  An oily plug is usually bad rings (I know you already know this - just typing out loud, here).

That's all I've got......

Last edited by Gordon Nichols

If it's carbon (I'm utterly inconvenienced) in one cylinder, the engine needs to drop out of the car. If it's a flat exhaust lobe (again, seems like a stretch), the engine needs to drop. If it's really, truly two HUNDRED and fifty pounds, on a compression test-- the engine is almost assuredly going to need to drop.

The only scenario I can envision where the engine stays in the car is if the gauge was broken by the time it got to that cylinder. 

I don't see how you'd get a big carbon build-up in 16k miles. And the sudden onset of metallic noise also indicates something acute, not a chronic thing. 

I see you checked the pushrods but I'm going to say the #2 exhaust valve does not have rocker engagement. I think Kelly had something like this go wrong on his car last year; one of the elephant-foot adjusters got spinned around wrong and his engine laid right down. 

You lose #2 and then the other three slugs have to work against it AND push the car. Now you're on the pedal and pouring fuel into her, everything is heating up, you get some blow-by, etc. etc. 

Such are Ed's theories, which are worth exactly what I charge to dispense them...

WOLFGANG posted:

With 250 psi in one cylinder and normal in the rest, the exhaust valve must not be opening at all.  Wonder if you turn engine over with valve cover off it you could see that that exhaust valve was not opening? Could it be a wiped exhaust lob on that valve. 

Wouldn't you have the same compression on cylinder #4 then? #2 and #4 use the same lobes.

Gordon-Thanks for the inquiry about the engine. Like you I prefer to do my own work-I really don't want anyone else messing with my tub. I just completed the eighth month of  chemotherapy which leaves me weak-normally I'd have the engine out by now. I brought the car to this shop because they have a good rep. and have a lift. They told me that if I brought it in last Monday which I did they would get right on it. It is now sitting in their shop-at least it's inside. They are busy so I have to be patient.

Thanks everyone for their suggestions and when I know more I'll pass it on.

Joel

LeonChupp posted:

Here"s my .02 on the High Comp. reading......    Could the exhaust valve be seated and not being opened by the cam, lifter, rocker system????   That would surely cause an increase in pressure.....   Never seen it, but it fits the picture...

Joel hope you get better man.

I think the valve stem would have to be broken off and completely out of the way and I don't think the valve guide would allow that to easily happen. I suppose it could under some freak circumstances but wouldn't the valve fall into the cylinder? Hell, I just found out Hugo Boss made all of the uniforms for the Nazis. It's no wonder those guys were so well dressed but what does that have to do with this topic?

Last edited by Rusty S

Hugo Boss also designed the Porsche Factory Racing Team's outfits - Very Black and Very Classy.

Get well and get rested, Joel.  THAT's what's important, not the car.  It might be something as simple as an adjuster loosening up and not working the valve.  We'll see when they get to it and I won't bug you further.  A very good friend, my age, is about at the same point as you with her Chemo and I am in awe of the strength of people who go through it.

All the best.  gn

Engine Update

After testing  compression with 3 different gauges and scoping it with 2 scopes the shop pulled the engine and found that #2 was loaded with carbon (Alan was right).They told me the piston,rings, cylinder and head were fine so they cleaned it up,lapped the valves and put it together The compression is now normal on #2 and all 4 cylinders are close and very acceptable-I forgot to ask the readings!

They also found #2  intake manifold to head gasket almost gone (sucking air) as were most exhaust gaskets. The spark on #2 &#1 is weak so will change distributor (wires and plugs ok).Also discovered was a broken pressure plate (springs?). I noticed that the arm where cable attaches to was in a weird position when I replaced the cable about 3 months ago but clutch worked fine so I forgot about it.

After it goes back together they will address the Webers-#2 idle mixture brass seat has come loose on occasion-now awaiting parts and gaskets.

Thanks everyone for the well wishes on my chemo-it is working (blood count improving) but I experience a lot of the side effects of the drug Vidaza (fatigue a big one) but I'll take the tradeoff.

Joel

Good to hear from you, Joel.

I, too, amglad that they found a bunch of minor issues (well, OK, so the carbon build-up was a bit more than "minor", right?) and are getting them all fixed at once.  When you're feeling chipper enough to get out there speedying around, it should be trouble-free for you.  

And I agree with Wolfie - you've found a good shop, there.

Get better through the Summer.  Cool fall driving weather is approaching!

Joel,

Well this here has been a real ed-u-cation.  Sorry I missed the fun, as I would have been able to offer up a lot of completely useless information about what might be wrong.  Another under the heading: many ways to go wrong. Looks like only Wolfy knows how these engines actually work: two valves per lobe.  Genius design, if you ask me.  Anyhow, carbon build-up is the culprit.  Did I miss how this got started?  Bad plug wire??  and so, if I read right (it's late and I'm moving fast) it's fixed.  Now if we can just get your old bod to sort out too, all will be good.  Sure hope that turns out right.

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