Rough running engine

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cuffy
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Rough running engine

Post by cuffy » Mon Jul 04, 2011 12:36 pm

Hello

After about 15 minutes of running my M201 engine starts to misfire, sounds as if its running on 3 cyclinders, starts to back fire. Switch off and leave for a few hours and things appear to be ok. As part of the restoration we've not done much to the engine apart from general servicing, this included replacing points, the condenser and plugs as the original ones were very badly warn. We have several theories, dodgey coil or points or condenser. We are planning on starting with pulling distributor apart, however I could do with some advice before we start:

1. Are condensers voltage sensitive? I ask as my spares supplier tells me that a 12V one will work fine in my 24V M201.

2. Looking in my Willy service manual the coil is part of the distributor? Is this correct?

3. Any other suggestions?

all advice much appreciated
Mike C
Hotchkiss M201
Modified Wrangler


Awd261
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Re: Rough running engine

Post by Awd261 » Sat Jul 09, 2011 9:11 am

hi

PM sent

all the best :D

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artificer
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Re: Rough running engine

Post by artificer » Sat Jul 09, 2011 9:55 am

Is the manifold heat valve free to open & close?
Why would you be dismantling the distributor?
Check for loose connections & poor earths/grounds.
John GIBBINS Member Institute of Automotive Mechanical Engineers [Ret], ASE Master Medium/Heavy Truck & Auto Technician USA -2002 Licensed Motor Mech NSW MVIC 49593 Current 2015
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.

docdoom45
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Re: Rough running engine

Post by docdoom45 » Sun Oct 02, 2011 10:00 am

Hi there,
Have you checked the cylinder presure cold and hot.
Maybe it is just a valve clearance problem.
Just thought I would chuck in a 2 pennyworth though.
Dave.

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Ingo
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Re: Rough running engine

Post by Ingo » Wed Nov 16, 2011 4:48 am

Had problems, that sounds equal. Outlet valve on cylinder No. 4 wasn´t working. We found that out cause we tewsted compression. 3 was ok, 4 not, no head gasket problems.

Now runs excellent.

Cheers
Ingo
MB January 1945

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andym201
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Re: Rough running engine

Post by andym201 » Tue Nov 22, 2011 2:29 pm

Here's a couple of other things from experience to check before turning to drastic action like inspecting valves.

The points gap may be correct but also check the static timing. Should be about 5 degress BTC. I say this because in dealing with one jeep that ran rough, misfired etc after new points had been fitted and correctly gapped. Turned out that at some point in the past the timing had been set up with a points gap of only 15 thou ! Intreagingly the symptoms were very similar to a leak on the inlet manifold.

The other rogue to check is the crank case breather valve assembly. One of my jeeps 'died' and would barely run whilst I was away at a show. Took a while to puzzle out but removing the pipe from the valve to the crank case side cover then taping up the union hole in the breather valve with several layers of insulating tape saved the day and it drove home perfectly.

The valve inside is spring loaded and opens to clear fumes from the crank case only under high vacuum (on over-run). If it fails so much air is drawn in from the crank case making the mixture very weak that the engine will hardly run. It's easy to check - remove the pipe and put a finger over the hole - if the problem goes away the valve is likely to be peranently open.
1957 M201 army serial 02743 Hotchkiss serial 3472
1963 M201 106SR army serial 22168 Hotchkiss serial 23815
1953 Delahaye VLR no. 07821
Always looking for Hotchkiss numbers for the database - please email me to help by providing details of your M201


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