TheSamba.com :: View topic - Hydraulic Lock ( Yes ) Pic of what happened

Sun Oct 26, 2008 4:46 pm

Just now started the engine and it turned over, hit a real hard spot but it went on over and started (I have a HD starter). Ran rough for a couple of seconds ( this is what led me to think hydraulic gas lock ) then cleared up. Just one small detail => It then had a knock. Not loud but definite. I shut it down after I went back to listen closer. Ran about a minute total. Checked valve clearance which was a little loose, but the engine had some warmth to it by that time. Pulled rocker arms to get push rods out hoping for a bent push rod, no luck. Pulled plugs, cranked without plugs or rockers and can not hear the knock. This is a new 2110 with about 300 miles and I have been fighting the IDF's to get the tune, so after one probably leaked and did this, I was so mad I had to just put everything down and walk away so I did not inflict injury to them.

When I go back out to the garage, what should I check next?
I was thinking of putting the rockers back on, and checking compression next.
Can hydraulic lock bend a valve? An H beam rod? Heaven forbid a crank?

Sun Oct 26, 2008 4:59 pm

you said hyd lock....it filled with gas?!?!? :idea:

Sun Oct 26, 2008 5:06 pm

i wouldnt think the starter would have enough tork to bend a rod , but i could be wrong

Sun Oct 26, 2008 5:23 pm

orangerail wrote: you said hyd lock....it filled with gas?!?!? :idea:

Yes, if a carb leaks gas into a cylinder it will not compress like air.

padex wrote: i wouldnt think the starter would have enough tork to bend a rod , but i could be wrong

I wouldn't either, but I was more concerned with the other 3 cylinders providing the power to do so while it cleared the gas out of the 4th one. Just trying to think of things the knock could be, such as the piston clearance at BDC if a rod bent.

Sun Oct 26, 2008 5:29 pm

If it did lock, you might have bent a rod or the crank. Only one way to find out... :cry:

Just another reason to go with injection, if you ask me. Not saying this can't happen with electronic injectors, but it's a whole lot less likely.

Sun Oct 26, 2008 7:38 pm

miniman82 wrote: If it did lock, you might have bent a rod or the crank. Only one way to find out... :cry:

Put the rockers back on.
Compression is good.
Installed plugs.
Still had knock.
Took belt off just in case it was alt / fan.
Knock.
Removed dist & drive since I don't need it anymore.
Knock.

Sounds like the same sound a rod makes with excessive bearing clearance except a little sharper.

I will have to tear it down. :cry:

Can I get the shroud up high enough to be able to get the heads off without taking the engine out, just in case it is in the upper end? Its a '70 with a factory doghouse.

Sun Oct 26, 2008 7:41 pm

Check for a snapped or pulled head stud before you get too far into the engine.

Sun Oct 26, 2008 7:42 pm

Will do, thank you.

Sun Oct 26, 2008 7:59 pm

Alexander_Monday wrote: Can I get the shroud up high enough to be able to get the heads off without taking the engine out?

My common sense tells me to pull the engine if you wanna pull heads.

Mon Oct 27, 2008 5:40 pm

Just tore the heads off. I had a 50 50 shot and it was not found with the first one.

It apparently lifted the head enough that at the same time it moved one of my copper gaskets.
I am running 0 deck without them ( .063 with ) and the piston was hitting the gasket just barely when it would run.
That is why it would not make the noise cranking, it was just barely hitting once it got a little warmth in it.
You can just see the outline of the piston edge on the gasket.

The CE gaskets are smaller than the CB head bore, but I figured if I assembled them in place they would stay.
Wrong! :cry: Stupid stupid idea.

Guess I will call CE and see if they can make a gasket to fit the head bore and cylinder bore.

Now as for that carb, :evil:

:?: What should I do to make sure the carb does not do this again :?:

:?: Also, I have not turned the engine, so should I worry about the seal at the case :?:

This engine did not leak a drop of oil, which I was kind of proud of.

Well, back to the garage to move things so my Wife's van can fit back in.

Mon Oct 27, 2008 6:32 pm

The studs are probably compromised too if it lifted enough to do that.

What you have to do is find out why the carb is doing this and stop it. The only reasons are a carb that is leaking gas from a defect, or a float overflowing due to a leaky needle and seat or float problem. Figure out what is wrong with the carb.

Mon Oct 27, 2008 7:18 pm

I always fit an LPG kit fuel cut off solenoid to vw's (paricularly kombis) as I have had a few syphon the tank into the crank case

Mon Oct 27, 2008 7:34 pm

Interesting that the studs were still torqued good and no sign of pulled
inserts. According to what I have read. the torque goes up considerably
when the engine warms up, so maybe since the engine was cold, the stretch
was within the range they did not deform. They are CB 10MM chromoly
studs. I will email Pat to see what he thinks about the possibility of them
being compromised.