Crankshaft Endplay Type4 Engine

[atchman]

Hi All,

This is my first post and I am not really a mechanic, so not hugely knowledgeable about engines so please bear with me.

My mechanic, who I would not class as a air-cooled expert, says that there is huge end-play in my crankshaft on my 2L 1979 bus, with a type4 CU engine inside. He says he can see this only when rotating the engine using the large nut on the alternator pulley (while the engine is in the van).

I had another air-cooled guy look at the engine and he said there appears to be no excessive endplay. To prove this he grabbed hold of the large pulley wheel and tried to yank it back and forth - it seemed pretty solid to my eyes. The engine is running well, plenty of power and the sparks are a nice brown color.

Is my mechanic misreading something by rotating the engine and confusing the action as endplay in the crankshaft?

Thanks..

[SGKent]

put your location in your avatar or your sig line.

you can actually put a dial indicator on the pulley using a magnetic base on the tin shroud and measure the end play. It is not an optimal way of doing it but it will be close.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Abscate]

Crank endplay isn't really indicated by running condition until its too late to do anything about it...whump thump thump..

You can JUST feel 0.001" of endplay, 0.004 of endplay is noticeable by most as movement. I don't know specs on the Type 4 motor but just because the motion is noticeable doesn't mean its bad.

Guide yourself more by history - how many miles on the case, how has it been driven, last overhaul, who did it, what does the workmanship look like?
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[SGKent]

[atchman]

Hi

Thanks for the prompt replies. The engine is a recon that has now done 30K miles. At around 25K miles it had to be taken apart and have one head replaced and another reconditioned because it had burnt valves. I believe this was due to poorly maintained Solex carbs. I subsequently replaced the carbs with Webber ICTs (145 mains, 55 idles). New replacement distributor, electronic ignition.

Anyhow, my mechanic is suggesting that he can see endplay when rotating the engine while adjusting the valve clearances. However when I try to forcefully to move the large pulley wheel I cant see any play whatsoever. Do I need to remove the belt, should I be rotating the engine using the big bolt on the alternator pulley to see play?

I am located in Ireland. My bus is a 1979 T2 Camper. Ill update my Avatar now.

Thanks

[SGKent]

don't know what to say. If he is a friendly guy maybe he can show you what it is he is seeing.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]

With the tranny in neutral use a broom handle or something to force the crankshaft forward in the rig. Don't apply so much force that you are at risk of damaging the fan. Now place your fingers so that they span the gap between the fan and the fan housing and have someone push on the clutch. If you feel no movement or if the movement is almost imperceptible then you are fine. Repeat as necessary until you are satisfied you know what is going on.

Note that if the crank was correctly shimmed to start with you can not correct excessive end play by changing the shims, instead just live with the problem until the oil leaks or other problems become excessive.

Type 4 engines don't typically develop excess endplay as is common for Type 1 engines.

[Abscate]

I think the alternator belt has to be off to make this rough measurement. In theory it 'shouldn't matter" in practice, its decomplicating to remove it.
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[atchman]

Thanks all,

Ill do some more investigation and let you know how I get in. Will report back in a 3 days time.

[atchman]

Ok so went and checked this on my van. When I grab the pulley and try to rock it back and forth there is no movement. However when I take a wrench and rotate via the alternator bolt you can see the big pulley display some lateral movement as you rotate. I would say about 16th of inch. Am I seeing the signs of a bust crank?

[Wildthings]

[atchman]

Im not hearing any unusual noise. Does the engine need to come out, should I stop driving it? Is this a big fix?

No oil leaks. Are there any more tests I can do?

[Abscate]

Is it translating 1/16 inch or could just be slightly out of round?
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[Busstom]

atchman, help us help you by correcting your terminology: when you say you grab the pulley and "rock" it back and forth, that doesn't make sense...if you're troubleshooting for end play, you should be shoving-and-pulling the pulley fore and aft, right? Because end play is in the axis from the front of the Bus to the rear, so rocking doesn't apply.

Additionally, when you say you see "lateral" movement of the pulley when you rotate the crank via alternator, I think what you're actually seeing is either a slightly bent fan or pulley, or a pulley/fan assembly that is misaligned, and so the pulley may not be rotating concentrically, or in a more simplified description, sort of "wobbling." Either way, neither of these have anything to do with (nor affect) end play.

That said, if you want to troubleshoot a bent or misaligned pulley, disconnect the coil wire and have a partner crank the engine while you observe the pulley rotation, I'd bet you'll see the oscillation back and forth (what you call lateral movement). If so, that's another issue that may need to be fixed...but that's not end play.

Also, with the intake screen removed, and the engine running, have someone push in and out fully on the clutch...you shouldn't see much fore-and-aft travel of the pulley. If not, and you can't feel/see play when you push/pull by hand, then your end play is probably just fine.

Watch your fingers, don't grab a running engine or belt, and be safe!

[atchman]

Hello, thank you again for your replies. I will spend some more time this weekend diagnosing. I may even take a video. Apologies if my descriptions are poor, I am not that savvy about engines. I ultimately think my mechanic is wrong because if I had as much end play as he is describing then I would expect erratic engine behavior and even oil leaks or loss of oil pressure. Also the bus is driving great and sounds perfect. So Ill try your suggestions and let you all know how I get on. Thanks!!

[Tcash]

Too much End Play

Link


A human hair on average is 0.05mm (.002") to 0.10mm (.004") thick.
End play specification is 0.07mm (.003") to 0.12mm (.005")

GD
Tcash

[atchman]

OK, I tested the compression of the engine today, it reads circa 110 PSI on each cylinder with the engine cold. I am beginning to think I just have a slightly bent or even loose fan hub. Is this something I will need to pull the engine out to take a look at?

[Tcash]

Grab a hold of the fan and try and shake it. If it is loose you will feel it.
Good luck
Tcash

[SGKent]

do you own a torque wrench and set of sockets, and an extension.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[timvw7476]