Beetle sounds like a diesel after intake replacement

[VW1300]

I have a '66 beetle - the SP intake heat riser is clogged resulting in carb icing so i picked up a new intake from JBugs - EMPI brand and put it on with new crush seals at the heads. It didn't seal up very well - I see now that the EMPI intake needs some work for the end flanges to press down on the intake ends evenly. The crush seal on the right head was unevenly crushed. The car did run OK although was a bit low on power.

While I modify the new intake, I figured I'd put the old intake back on with new crush seals. Did that - tightened down ends more than snug but not way tight etc. Now the car barely idles and sounds like a diesel - just awful. I know that the old intake can go on properly - it was that way for 50 years or so - are the regular cheap crush seals considered OK, or is there a better option? Might I have damaged something internal already trying to diagnose this? Any tips for putting on a SP intake manifold?

I tried spraying starting fluid at the intake ends when the engine is running, but no real change in RPM was noticed, although it's running so bad it's hard to tell for sure. Timing light says all 4 spark plugs are firing. Just did a valve clearance check a month ago.

Thanks for any ideas -

Charlie
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1966 VW Beetle

[67rustavenger]

Did you remove the old manifold gaskets? Before installing the new ones?

You do realize that, aftermarket parts fit like shit!

Clear out the heat risers on the original manifolds and never look back.

I have no idea why a gas engine would sound like a diesel.

Good luck
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[mukluk]

If the engine is rattling like a diesel, you may have accidentally dropped something into one of the head intakes while swapping out the manifold. I wouldn't run the engine anymore until you inspect the intake valve area and chambers for possible foreign debris.
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1960 Ragtop w/Semaphores "Inga"

[VW1300]

I did remove the old gaskets each time. I can say the first time the vacuum leak was a normal vacuum leak, and the right crush gasket was not crushed evenly. Regarding cleaning my current intake, the metal that holds the crossover pipe to the intake pipe is cracked so I wanted to replace it. I bought a used German intake but could not unclog it, tried all the things people tried on other threads. I gave up and bought an EMPI but it was not ready right out of the box.

I'm not missing any pieces/screws/nuts etc and don't know if I dropped anything down either intake port, but I suppose I can check compression to see if something got really damaged. I don't know how I could inspect the intake chambers with the engine in the car though. I guess I could try to vacuum them out?

I think I have another set of crush seals and will do the job again...I'm hoping that the current set didn't crush evenly for some reason. If they did crush evenly, I will assume something got in the intake and will likely be back here asking about what to do next.

Thanks,
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1966 VW Beetle

[TDCTDI]

As previously said, it sounds like something fell into the engine when you had the intake off. Remove the spark plugs & see if any of them look bent or damaged, if so, that would be the cylinder that has something in it.
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[mukluk]

[61SNRF]

As suggested remove plugs for inspection you might see evidence of interference.

With the plugs out also do a compression test to look for low readings.

With the plugs out turn the engine over by hand to check for unusual noises or tight spots.

Check the valve adjustment again, if any are real loose could be something trapped under a valve not letting it close.
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-Bruce

An ounce of prevention is worth a pound of cure.

[VW1300]

Great ideas, thanks to all. It will be a few days until I get to all of these but will report back with my findings.
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1966 VW Beetle

[VW1300]

I ordered one of these, should be here by the end of the week:

https://www.amazon.com/gp/product/B07MBXSMVQ/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1

the plan is to remove each spark plug and inspect the inside of the cylinder as best I can & check compression for each.
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1966 VW Beetle

[VW1300]

Update: Checked compression - 95, 110, 110, 110. A little concerned about #1 but it should fire up and run with a lot less drama. All the valve clearances are OK - also no bent pushrod tubes or signs of damage.

Tried the endoscope - very interesting little tool but didn't see anything out of the ordinary down in the cylinders.

Took off the fan belt and started the car - banging noise was still there, so ruled out something caught in the fan. Put the belt back on and banging went away next time I started the car for about 10 seconds, then came back.

With no obvious signs of mechanical damage, I'm now thinking it might be a combination of intake and exhaust leak. During that 10 seconds of no banging, I could still hear a blatty exhaust note. I know the muffler is at least 35 years old, so this rough running from intake leaks could have punched a hole somewhere that was already getting weak, like the seals or somewhere? I did notice a hole in the right side tube running up to the (clogged) heat riser - see photo. Don't know how long this has been here but it obviously isn't helping:

IMG_1710 by vw1300, on Flickr


Here is a link to a video with the car running - any comments or further ideas are greatly appreciated.

Charlie

IMG_1711 by vw1300, on Flickr
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1966 VW Beetle

[toxicavenger70]

That sounds bad. If it was my car I would stop running it and pull the heads off asap.

[VW1300]

Update: pulled off the intake again and found the left side had not sealed properly, there was a black stain on the seal. Cleaned it all up and put another set of crush seals on - sourced from mid-America - these seem to be a little more girthy than the previous set I had. Put everything back on and the banging noise has reduced to a much less alarming level. Car starts and idles easily and steadily.

Checked for leaks in exhaust with soapy water in a spray bottle - some leaks around right heater box-to-muffler joint. Tried to tighten everything down as best I could and it seemed to help a little. The hole in the muffler tube that leads up to the right heat riser connection is concerning though, I can feel the exhaust pulsing strongly if I put my thumb over it. This muffler is at least 35 years old and although I hate to do a diagnosis through replacement, I think it's time for a new one with new seals etc.

Is there a preferred source for a stock muffler?

charlie
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1966 VW Beetle

[VW1300]

Update #2: Installed a different used intake with intake-to-head crush seals from mid-America - these work best if they are seated into the recess on the head, I did this by super-gently tapping the gasket into the recess with a 27mm socket. Once it's in there it won't come out accidentally and get mis-aligned. Seals from other source tended to move around in the recess and thus tended not to seal evenly.

Also installed new stock muffler (Dansk, fit was fine) and muffler gaskets etc. After all this, the engine sounded better though I admit I don't really know what was wrong.

At this time (beginning of June) my generator died (only 2.5 years old) and I had to wait 3 weeks for a new one to arrive due to shipping delays. That install went fine.

I did a tune-up by adjusting point gap and put on a new distributor cap I had, and set timing. Engine sounds a LOT better though I can hear a small exhaust leak somewhere (a slightly blatty exhaust note) but can't seem to track it down. Checked for intake leaks but can't find any and is showing no symptoms of those anyway.

I've been driving it and it feels good like I'm firing on all cylinders, so I'm going to not worry about it and assume I have a slightly freer exhaust. Thanks to all who replied with ideas and suggestions.

Charlie
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1966 VW Beetle