Engine compression

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Model T Ford Forum: Forum 2005: Engine compression
Top of pagePrevious messageNext messageBottom of page Link to this message  By Leo on Wednesday, March 12, 2008 - 12:15 pm:

Hey all, I recently bought a 15 touring. I have not yet started the engine because Im in the process of tunning everything up first. Last night I checked the compression and it only built up to 30 psi. What should I do about this, I read that 45 to 50 ideal. Thanks Leo.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Bunner on Wednesday, March 12, 2008 - 12:49 pm:

install new rings, then check again.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Michael Bunner on Wednesday, March 12, 2008 - 12:49 pm:

before then, you could also try and tighten the head down some more...


Top of pagePrevious messageNext messageBottom of page Link to this message  By cecil paoletti on Wednesday, March 12, 2008 - 01:30 pm:

A competent auto repair manual will provide detailed instructions an how to conduct a compression test and analyze the results. Following such a process should give you some insight as to how to proceed. Possibly valves could be hanging up, rings could be stuck, or the head gasket leaking. There is also the possibility of a crack in the combustion chamber. I'd suggest adding some kerosene to each cylinder and letting it soak into the rings, then change the oil to a 5W-30 product and crank vigorously. Finally rerun the compression test. I would be very much surprised if the engine will start if all the cylinders are that low on compression. Good luck.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Vince M on Wednesday, March 12, 2008 - 01:47 pm:

I would run the engine a while first and get things lubed and warmed up. An engine that has been sitting for a length of time can show reduced compression. Also could be a valve sticking or not fully closing. Definately run it first.

Vince


Top of pagePrevious messageNext messageBottom of page Link to this message  By steamboat on Wednesday, March 12, 2008 - 02:00 pm:

Checking the compression on an engine that hasn't been run recently may not mean much. Try to get it running and check it again. Then while the engine is warm, has oil on the piston rings, the rust and carbon has been blown out of the valves, the compression will probably improve.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem on Wednesday, March 12, 2008 - 02:18 pm:

Vince and Steamboat have the right idea. That is, run it first.


Top of pagePrevious messageNext messageBottom of page Link to this message  By cecil paoletti on Wednesday, March 12, 2008 - 09:22 pm:

If you are unable to run the engine first you might consider removing the plugs and towing the car a short distance. Lubricate the cylinders liberally with a good upper cylinder lubricant (Marvel Mystery Oil? Kroil?) before towing though. A quick visual inspection of the valve position can be made by removing the valve cover and placing the piston in firing position for each cylinder. This can be determined easily by noting the timer position. Each cylinders valves should be fully closed, a bit of carbon on a seat or a bit of varnish on a stem could hold a valve open, check the valve lash, when the timer & piston is in firing position. Sticky valves aren't unusual for T engines that have been out of use for some time. A cold engine will test low on compression but you are looking for uniform pressures. A bit of cobbling with pipe fittings would allow applying air pressure to each cylinder in firing position then listening at the exhaust and carb would give an approximation of the respective valve condition. Honestly though, it might be easier to just pull the head and take a look. Hope it fires right up for you.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Mikeska on Wednesday, March 12, 2008 - 09:38 pm:

Leo,

Did you have the throttle completely open when you did the compression check?

Paul


Top of pagePrevious messageNext messageBottom of page Link to this message  By Leo on Thursday, March 13, 2008 - 01:35 pm:

Thanks to allof you, Im going to work on getting it started tonight, ill post the outcome. Leo...


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