Flat Cam???

[72squareguy]

Can someone please tell me the symptoms of a flat cam? What happens??
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72 F.I Squareback
70 Beetle Daily Driver

[Glenn]

Valves don't open.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

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[72squareguy]

[Glenn]

It will only run on 2 cylinders.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

#BlueSquare

[slalombuggy]

Easiest way to see if a cam is going flat is to do a valve adjustment.

brad

[Danwvw]

Yeah, they start knocking and you wind up with like a 1/4" of valve to lifter clearance. They loose a lot of power but will keep running. It happens when you run an engine that's been sitting a while and has gotten water in the oil that rust out the cam. It will be fine for a while then ware down very quickly. Not too big a deal just a rebuild with new cam and lifters.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[modok]

The valves on that lobe don't lift as far as before

[vwracerdave]

The engine will sound horrible and shake more.
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2017 Street Comp Champion - Thunder Valley Raceway Park - Noble, OK
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[Vanapplebomb]

As already mentioned, regular valve adjustments will tell the tail. Keep a record or how much take up you do at each valve adjustment. When you notice you have to take up more and more last, you know the valve gain is wearing badly, and it is most likely the cam/lifters.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[Dougy Dee]

You'll also have a gray metallic smear in the oil.

Your magnetic oil drain plug will attract some of that smear.

A rebuild will require drilling the oil galleys and a new oil cooler to clean out the crap!

[Multi69s]

As mentioned above, you will get too much valve clearance. However, what was not mentioned is that it will occur on the two opposing cylinders at the same time. 1 & 3, or 2 & 4 since they share the same lobes. However, the two sides may still have different clearances. This is because as the cam start to go flat, it usually takes the lifters with it. So you can have more valve lash on 1 than 3. That is because the #1 lifter has worn more then the #3. I have seen this clearance grow to such a point, that the pushrod actually falls out of the rocker arm.
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[Max Welton]

Also, as a lifter is going away the grit is going through the rest of the engine and chewing up all the bearing surfaces.

This is a good reason to run a filter.

Max
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[Multi69s]

Actually, it doesn't shake and run as bad a you think until the cam goes almost to a circle. True story:

Back before I joined the Samba (pre 2006), I had a very important meeting in Los Angles. I live in the Central Valley (elevation 0), to get to LA you have to drive 300 mile and through the Grapevine. The Grapevine is a very serious mountain range, where the elevation changes over 4000' in a very short time. If you want to test your engine this is the place. At the time, I was running a 2010 in my DD that had about 20K miles on the engine.

I hit the steepest part of the grade, and opened her up (I love passing new cars). 3/4 of the way up, I start loosing power (look at gauges - OK). Head for the nearest off ramp, and as soon as I got on the off ramp, lost a cylinder. Pulled into a parking lot, started checking things over - no external problems, started cranking the engine and heard a weird noise. The first think that popped into my head - Broken push rod. Pulled 3/4 valve cover and the #4 intake pushrod was out of the rocker arm.

I blamed it on myself, screwed up during last valve adjustment. Connected everything back together, adjusted valve lash by feel and made it to my meeting. It was a 3 day meeting, and I explored LA every night after the meetings, then time to head home. This time I never made it to the grapevine before loosing power. Pulled over popped off 3/4 again, no problem. Popped off 1/2 valve cover, #2 intake way loose. Adjusted it by feel, then drove the 300 mile home.

Once I got home time to diagnose the problem. Even though I had building VW engines for 20 years, at this point in time I was out of the social media. No Hot VWs, no Internet, did not know about the ZDDP issues. After thinking what was the commonality between 2 & 4, I thought cam. Pulled off a rocker cover and didn't need a dial indicator to see that the lift was way off. The ironic part was with all of this going on, the engine was not running that bad, no shaking, and seemed to drive fine. I wasn't pushing it though, because I suspected something was amiss.

Here is a picture of #4 intake lifter.

_________________
69 road Bug 2110
73 Squareback - 2L, T4, Automatic W/ AC
Gone, but many fond memories 69 Baja Bug 2010 - 5 Rib Bus Transaxle
Gone but not forgotten 72 Baja Bug 2010
My builds
T4 into Squareback http://www.thesamba.com/vw/forum/viewtopic.php?t=458944&highlight=
Auto Trans Rebuild http://www.thesamba.com/vw/forum/viewtopic.php?t=516066&highlight=
AC in Squareback https://www.thesamba.com/vw/forum/viewtopic.php?t=...highlight=

[Pruneman99]

Can you send that lifter to me? I need a new salsa bowl

[[email protected]]

I had an engine I built in the late 80s (1776) and the engine seemed a lot more sluggish 60k mi later.

I tore it down, and found the W110 cam was lifting the valves around .150".



Everything looked great, but the lobes were a fraction of their proper size.

The engine ran very smooth and quiet, just way down on power.

Not all "flat cam" situations are catastrophic.
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