Halftrack engine problems

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emptyhead2
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Halftrack engine problems

Post by emptyhead2 » Sun May 21, 2017 3:22 pm

Short story engine running rough only firing on three cylinders1,2 and 3. Wound up pulling plug wire 4,5and 6 al together and no change in the engine running. Pull either 1,2 or three and the engine stalls.Getting spark to all cylinders replaced head gasket three times replaced intake/exhaustgasket.points fine replace distributor cap rotor.new plugs and coil.ran compression test on all cylinders not running and all where with in 115 psi. Ran compression test with engine running and after bleeding off the guage and letting it come back up to pressure last three cylinders where at between 45 and 60. First three came back up to 115. Went and checked valve lash and at tdc can't even get a 10 thou feeler guage in, let alone a 40 thou. Should I be getting at least 40 thou cold on any of the cylinders at tdc. Posted over at HalfTrack info also. Any help would be great.

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Re: Halftrack engine problems

Post by G102 » Mon May 22, 2017 4:18 am

Do a DRY compression test

Then
Take a oil can and give each cylinder 3-4 large squirts or oil , enough to cover the piston good so the rings become sealed with oil and let me know that the compression test is WET.

When the engine is running is there a lot of "BLOW BY" coming out of the oil filler tube?

This needs to be done first , I can't help you on half track info, I'm banned from this site
Thanks
GARYS HALF TRACK PARTS

emptyhead2
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Re: Halftrack engine problems

Post by emptyhead2 » Mon May 22, 2017 1:04 pm

When I do the test dry with out running the engine all cylinders are within 5 psi of each other. About 115 120. I do get blow by coming out of the breather cap when it's running, more then I thought was good. I only get the low reading on the last three cylinders,4,5and 6 when it's running. Are the lifters suppose to bleed down after awhile. Thanks

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Re: Halftrack engine problems

Post by G102 » Mon May 22, 2017 2:22 pm

Just a simple compression test please, COIL WIRE REMOVED, NOT RUNNING. Forget about lifters and everything else. Just do a dry and wet test
IE
CYL-1
Dry
Wet

CYL-2 same thru #6
Gary

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Re: Halftrack engine problems

Post by jesse » Mon May 22, 2017 8:14 pm

Could be bad condenser. Don't use NOS. They don't age well. Jesse.


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Re: Halftrack engine problems

Post by G102 » Mon May 22, 2017 9:42 pm

A bad cond. Will let the engine idle but miss as soon as the rpm go up
Gary

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Re: Halftrack engine problems

Post by Old Dodge Guy » Tue May 23, 2017 6:39 am

Get the valve lash set correctly before getting too far into this problem or you will just keep chasing yourself in circles. If the valves are set too tight, they can not seal well enough to get good compression.
Have you observed the lifters actually moving the valves? Did they move smoothly?
You state that you changed the head gasket. What did the cylinders look like when the head was off? Piston tops clean or exceptionally dirty? Side walls scuffed? Any damage showing?
Adjust the valves correctly and then try the compression test, and let us know the results.
All the best, ODG
Still crazy after all these years.
The OD bug bit me in 1970......and I have never been the same

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Re: Halftrack engine problems

Post by G102 » Tue May 23, 2017 8:27 am

with all that said a dry and wet compression test will tell you whats wrong.
adjusting valves on these engines is no easy task since a machine shop is necessary to grind the valve stem ends. unless the seats were ground or hammered down the valve lash is probably close to where it should be since there is such a wide measurement spec.
Gary

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Re: Halftrack engine problems

Post by Old Dodge Guy » Tue May 23, 2017 10:06 am

Gary, you are far more experienced in these engines than I am, it's been far too many years since I worked on one.
That said, when he said he can not get a feeler guage in to check the lash, I thought that was part of the problem.
Just trying to help. :D
Still crazy after all these years.
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Re: Halftrack engine problems

Post by emptyhead2 » Tue May 23, 2017 1:22 pm

Ok Gary I didadry and wet test
Dry #1. 121
2. 118
3. 120
4. 121
5. 119
6. 119

Wet #1. 121
2. 119
3. 122
4. 122
5. 121
6. 122

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Re: Halftrack engine problems

Post by G102 » Tue May 23, 2017 1:40 pm

this is interesting,
you have more than enough compression for the engine to run, per the dry test

with enough oil sprayed in the cyl's to seal the rings the compression should have increased at least 20 psi.

if your valves were not sealing you wouldn't have readings as high as you do .

I just read your post from may 21 st and your saying the compression is 45-60 psi???

im lost. if you have compression down to 45 psi forget it, that's to low.

how much or do you have blow by in the filler tube

what did you see with the head off inside the cylinders and did you look at the valves closely?

I wish I could look at the engine, 3 cylinders are dead, there is something there that should stand out
gary

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Re: Halftrack engine problems

Post by emptyhead2 » Tue May 23, 2017 1:46 pm

I get what looks like blow by coming out of the breather. I only get the low compression numbers when the engine is running. I hook the guage up to one of the here dead cylinders start the engine and the guage goes up the between a 115 and 120. Then I bleed off the air in the guage and let it build back up and the dead cylinders only come back up to between 40 and 60 psi. I'm stumped

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Re: Halftrack engine problems

Post by G102 » Tue May 23, 2017 3:29 pm

Compression test is NOT done with the motor running. 3-4 revolutions and that's it. Piston rings are shot, if there was a large gap between the piston and the cylinder, or a ridge at the top,of the cylinder, this shows excessive wear, you probably have very worn pistons and probably crackdown rings, engines don't run with 45 psi.
The oil didn't seal the rings and the compression reading didn't go up . Should have been a minimum of 20 psi

Oil can't seal valves, A open or non sealing valve would basically have no compression

If your not sure hat your looking at with the head off, find somebody that does.

My guess is you need to pull the head and pan, push out all 6 pistons and see what all the parts look like
Gary

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Re: Halftrack engine problems

Post by rjbeamer » Tue May 23, 2017 4:03 pm

Maybe a little history of this engine miss is needed. Did this engine miss start from out of the blue or was there other maintenance or adjustments done prior to the engine miss starting.


Your compression readings at cranking are good. (As Gary said they should always be done at cranking speed not with the engine running.) I "am" concerned with your valve lash being less than .010" with Hyd. lifters. More info needed as to history.

Roger

emptyhead2
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Re: Halftrack engine problems

Post by emptyhead2 » Tue May 23, 2017 4:46 pm

Engine was rebuilt by engine rebuilder had done another halftrack engine already. New pistons and rings where installed block had been sleeve previously . New valves an seats. Lifters where rebuilt. Mains where line bored. Block was boiled and magna fluxed.ipurchased block from another person who sold there halftrack project. I picked up the engine as a short block from the shop. Didn't get to run it for ayear and half. Ran it a couple of time to check for leaks. Has zero mileage on it just start up in the garage. Been talking with the builder but he's stumped to thinks it might be the valves. Ran through all the usual suspects with ignition. Change distributor new set of wires plugs points cap rotor coil plugs etc.vacum guage bounces all over the place. Just stumped

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