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Question Hydraulic Lock Question

Did a brief search through past posts on H-Lock and have come across plenty of descriptions which, unfortunately I am experiencing -- cranking but no lift off, gas weep from the exhaust. If I let it sit for an hour or two, it eventually will kick off after the gas leaks out (which also concerns me that it is leaking past the rings as well as the valves and thinning the oil).

From the literature I read, it sounds like the culprit is possibly a thermal valve problem or a vacuum leak in that system.
For those who have dealt with this problem, what have you found to be the culprit more often?

I just rebuilt the top end and the car appears to be running pretty well (when not h-locked).

Old 10-09-2005, 10:01 PM
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Hydra-lock is usually caused by fuel leaking into the cylinders when the engine is not running. Usually caused by faulty carb needles/seats and some pressure from the fuel pump..........Never know it to happen with fuel injection......If you have it happen, it's important to get off the starter right away to keep from cranking and bending a rod....If you leave it sit and the fuel gets past the rings, you need to change your oil.......
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Old 10-09-2005, 10:06 PM
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Re: Hydraulic Lock Question

Quote:
Originally posted by ShoqAndAwe
-- cranking but no lift off, gas weep from the exhaust. If I let it sit for an hour or two, it eventually will kick off after the gas leaks out
no idea what engine you're talking about. Set up a signature.

Hydro lock can easily happen when manually air bleeding a CIS as when turning on the ignition and raising the flapper by hand. If the engine spins it's not locked. It seems something is flooding the combustion chambers though.

"thermal valve problem " may mean your engine is a MFI?
If so I have no hard info.. only what I've read around here. There has been some info posted about the engine rear mounted fuel pump leaking thru a seal.

as LakeCleElum said your oil will be diluted big time.
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Old 10-09-2005, 10:29 PM
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I will be taking a sample of the oil and checking it for any gas smell.

I still am curious as to what exactly leads it to h-lock.
Old 10-09-2005, 10:30 PM
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Quote:
Originally posted by ShoqAndAwe
I will be taking a sample of the oil and checking it for any gas smell.

I still am curious as to what exactly leads it to h-lock.
AS RoninLB said, we can't answer the question until we know if you have (1) MFI, (2) carbs, (3) CIS.............
work with us here!!!!
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Old 10-09-2005, 10:35 PM
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77 2.7 CIS

The engine does crank and gas does leak out the exhaust after a number of attempts to kick it off.
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Old 10-09-2005, 10:36 PM
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Sorry. Our posts are crossing in cyberspace.
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Old 10-09-2005, 10:36 PM
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If the engine is cranking you do not have hydraulic lock. Hydraulic lock is when one or more cylinders fills sufficiently with a liquid to fill the volume in the cylinder at top dead center or TDC - in the case of 911 engines this is usually gasoline as there is no liquid coolant in the system - since liquid is basically incompressible this causes one or more of the pistons to jam while trying to compress the liquid and the engine stops turning.

You appear to have a flooded engine (excess gasoline) caused by either leaking injectors, a cold start valve (CSV) that is always on, or an air metering plate that is jammed or defective combined with a air flow (AF) safety switch that is disconnected which allows the fuel pump to continue running even though the engine is not. The fuel distributor could also be at fault (jammed or damaged center plunger) but I doubt this unless someone has taken it apart or dirty fuel was allowed into the system.

Given your system worked before the engine overhaul I will conjecture you still have a wiring problem with the CSV and/or AF safety switch. Check the wiring per the instructions in my e-mail to you. I do not think a vacuum issue nor the thermal time switch (if that is what you mean by the thermal valve) is causing your problem. When wired up correctly, the thermal time switch still only allows the CSV to operate while the starter is cranking.

You also need to change your oil at this point as it surely has excessive gasoline in it. I would also disconnect the ground of the battery before making any wiring corrections in the engine compartment as it now is a fire hazard with all the gasoline and gasoline vapor about. Have a fire extinguisher handy and if indoors push the car outside to do further work on it.

Cheers, Jim

Last edited by Jim Sims; 10-10-2005 at 08:17 AM..
Old 10-10-2005, 08:10 AM
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referenced e-mail instructions for '77 2.7 l CIS to clarify this thread:

Check your plug wiring firing order; even if you think you installed them correctly check them again.

Check timing and point dwell (gap).

Check that you don't have the airflow switch and cold start valve connectors switched. AFS connector should have a green dot or be painted green and CSV connector should have a blue dot or be painted blue.

Prime the fuel system by having the ignition key to the on or run position; then lift up the air meter plate under the air filter and hold it until the tone of the fuel system whine changes and the meter plate stiffens. Do not hold the plate up longer than two or three seconds. Put air filter and cover back in place.

Try starting car. More later.
Old 10-10-2005, 08:46 AM
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Much appreciated. Will walk through all of it.

The car has run quite nicely just yesterday afternoon prior to letting it sit for a few hours. Went to start it and had a very brief start on first crank and then nothing---followed by gas out the exhaust. Knowing that it ran well, I wouldn't think it is impossible to have the firing order incorrect or the timing be too far off if at all?

Hopefuly, will chase down the gremlin and squash the bugger.

Fire extinguisher is always within immediate reach both in the work area and when on test drives.

Thanks for the help.
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Old 10-10-2005, 09:41 AM
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Quote:
Originally posted by ShoqAndAwe
I will be taking a sample of the oil and checking it for any gas smell.

I still am curious as to what exactly leads it to h-lock.
Leaky injector(s).
Old 10-10-2005, 05:53 PM
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Quote:
Originally posted by Jim Sims
Check your plug wiring firing order; even if you think you installed them correctly check them again. -- C H E C K E D

Check timing and point dwell (gap).-- C H E C K E D

Check that you don't have the airflow switch and cold start valve connectors switched. AFS connector should have a green dot or be painted green and CSV connector should have a blue dot or be painted blue.-- C H E C K E D

Prime the fuel system by having the ignition key to the on or run position; then lift up the air meter plate under the air filter and hold it until the tone of the fuel system whine changes and the meter plate stiffens. Do not hold the plate up longer than two or three seconds. Put air filter and cover back in place.-- C H E C K E D

Try starting car. - S U C C E S S
I had also pulled the plugs to see how much gas was in the cylinders - barely any. Also back pressured the flow through the fuel distributor by removing and plugging (briefly) the line from the distributor to the WUR attempting to unseat any junk that might have made its way to it.

Anyway, car is now running well (again). Many thanks for the help.

On to reconditioning the brakes....interior....tranny....
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Old 10-10-2005, 11:22 PM
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Quote:
Originally posted by ShoqAndAwe
I had also pulled the plugs to see how much gas was in the cylinders - barely any.
You don't have a hydraulic lock.
Old 10-11-2005, 05:17 PM
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Quote:
Originally posted by ruf-porsche
You don't have a hydraulic lock.
Thanks for the input. Yup, thats why I pulled the plugs to see how much was actually remaining in there. The cylinder was "wet" but definitely not a big deal.

Keeping my finger's crossed but so far, so good. Car has been running well during the break-in.
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Old 10-11-2005, 10:01 PM
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"Try starting car. - S U C C E S S"

You went down the checklist; did you find anything to correct? If not, you still may have an intermittent problem like a marginal electrical connector somewhere. Jim
Old 10-11-2005, 10:12 PM
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When I first bought my '79 SC, I ended up pulling the engine to fix a previously boogered exhaust manifold stud. Luckily I pulled the heads and when I did, I found that #5 had hydrolocked at some point bending the rod which was resulting in a piston scuff.

The previous owner had some non P-car experienced hack work on the car before I got it and my guess is that he lifted the flap allowing the cylinder to fill and thus hydro lock. I obviously checked all my injectors and the airflap switch etc etc before refiring my freshly o'hauled engine!
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Old 10-12-2005, 04:23 AM
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Quote:
Originally posted by Jim Sims
"Try starting car. - S U C C E S S"

You went down the checklist; did you find anything to correct? If not, you still may have an intermittent problem like a marginal electrical connector somewhere. Jim
Jim - Again thanks for the help and follow-up.

A few additional things I did was re-clean all the electrical connections on the Distributor and components with some rubbing alcohol. When I rebuilt, I found quite a bit of oil in the cap. I had cleaned all parts the first time but did it again anyway. Also, the ignitor three prong connection is not a very good/tight connection (#1 suspect) -- I also don't hear the whine which may or may not be an indication of weakening.

Tim - I think Jim is right - it wasn't h-locked. I think the ignitor three prong came loose during the initial drives. The reason I think this is that the car ran fine, turned it off, let it sit for a few hours, then no go.

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Old 10-12-2005, 06:43 AM
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