blown push rod tubes

Need some help with a technical problem - ask away and let's see if we can all help.

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Dean.s
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blown push rod tubes

Post by Dean.s »

It's a W code 1700 type 4 engine running twin weber 40's. Runs like a dream.

Until Sunday. Sitting at 70 on the motorway, checked the mirror and a big cloud of oily smoke!!!

Topped up the oil and made it home very slowly.

I got under it tonight and found the cause. The push rod tubes had blown out of the crank case. With a bit of force i can move the tubes into the case and back into the head, until the touch the underside of the rocker arms.

I've never had this happen before.

The crank case has an open breather topside so pressure should not be an issue.

Unless it could. Would a stuck pressure relief valve cause this?

If not what could?
1974 Porsche 914
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Re: blown push rod tubes

Post by Nine One One »

Are these the adjustable type?
Dean.s
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Re: blown push rod tubes

Post by Dean.s »

No they're fixed. i thought the heads would have a lip to stop the tube from slipping into the head.
1974 Porsche 914
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Re: blown push rod tubes

Post by Nine One One »

They are usually installed from the head down, it may be that whoever did it (if the engine was rebuilt recently?) tore the rubber seal, or used and inferior quality one? Usually some use the correct sealant as well, others use silicone, but you have to make sure the seal area is perfectly clean when installing them. Wonder if they were actually installed correctly in the first place, and oil has now got between the rubber seals and just worked loose?

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KS
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Re: blown push rod tubes

Post by KS »

Sounds like somebody has forgotten to install (or incorrectly installed) the spring clips that keep the pushrod tubes in place...

Take a look at this: https://www.thesamba.com/vw/forum/viewt ... ?p=8677394
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Bruce M
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Re: blown push rod tubes

Post by Bruce M »

Is the spring wire retainer fitted?
Goes under the valve cover area, and need to be fitted the correct way round.
Bruce M
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Re: blown push rod tubes

Post by Bruce M »

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neilbardsley
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Re: blown push rod tubes

Post by neilbardsley »

If that's the issue looks like a relatively simple fix. No heads off

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Dean.s
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Re: blown push rod tubes

Post by Dean.s »

Thanks for all the info.

I rebuilt the top end 4 years ago, using what was fitted. There's no retainer wire.

I had the engine on a bench and put the heads on after the tubes were seated in the crank housing.

Lesson learned. do more research!

Nice little fix for me to put right. ordered some loctite 565 too.

PS any recommendations for where to get the green viton seals from,?
1974 Porsche 914
Nine One One
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Re: blown push rod tubes

Post by Nine One One »

Never had an issue with the Elring sets. or a Victor Reinz Kit- VW Heritage? - Just Kampers?
70sThrowback
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Re: blown push rod tubes

Post by 70sThrowback »

if the above don't have them, try James Calvert at Stateside Tuning. He seems to have parts others don't.
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