68 Mustang No Compression In 3 Cylinders

[quote:9c497534ee="jfarrell305"]Evening,

First let me preface this by saying that I am at best a very amateur mechanic so I apologize if my terminology is incorrect and my question hard to follow.

I have a 1968 Mustang with the original 200ci 6 cylinder motor. The problem I am having is that I have very little compression on 3 of the cylinders and the other 3 are fine. Numbers 3 4 and 5 are the low ones and 1 2 and 6 are good. So of course the engine won't idle and runs very rough when given a lot of gas.

I thought that for sure it was a bad head gasket so I pulled the head. But the gasket looks fine. As does everything else. No visible cracks or holes anywhere. Everything moves appropriately when I manually turn it.

I am hoping someone may be able to shed some insight into what the problem may be because i am completely stumped. What could cause me to have no compression on 3 adjacent cylinders?

Thanks very much for your time,
Joseph~[/quote:9c497534ee]

Sounds like a worn camshaft-you sure it didn't jump time

Put it back on TDC compression stroke on No.1-check the chain and sprockets alignment. if its Ok-mike the camshaft lobed-one messed-up reading change it.

[quote:ea5e8602f1="rasmataz"][quote:ea5e8602f1="jfarrell305"]Evening,

First let me preface this by saying that I am at best a very amateur mechanic so I apologize if my terminology is incorrect and my question hard to follow.

I have a 1968 Mustang with the original 200ci 6 cylinder motor. The problem I am having is that I have very little compression on 3 of the cylinders and the other 3 are fine. Numbers 3 4 and 5 are the low ones and 1 2 and 6 are good. So of course the engine won't idle and runs very rough when given a lot of gas.

I thought that for sure it was a bad head gasket so I pulled the head. But the gasket looks fine. As does everything else. No visible cracks or holes anywhere. Everything moves appropriately when I manually turn it.

I am hoping someone may be able to shed some insight into what the problem may be because i am completely stumped. What could cause me to have no compression on 3 adjacent cylinders?

Thanks very much for your time,
Joseph~[/quote:ea5e8602f1]

Sounds like a worn camshaft-you sure it didn't jump time

Put it back on TDC compression stroke on No.1-check the chain and sprockets alignment. if its Ok-mike the camshaft lobed-one messed-up reading change it

BTW what is it- 289 or 302 whatever?

.[/quote:ea5e8602f1]

[quote:fc0fe42b84="rasmataz"]BTW what is it- 289 or 302 whatever?[/quote:fc0fe42b84]

Its 6 cylinder 200 cubic inch

First let me thank you for your response. Second I don't understand this part of it:

[quote:de254c0c8b="rasmataz"]if its Ok-mike the camshaft lobed-one messed-up reading change it.[/quote:de254c0c8b]

What exactly does that mean?

Thanks again,
Joseph~

Look at the book it will tell you the spec's for the camshaft lobes-use a micrometer and measure it from heel to toe the lobes should be all the same and in spec's if not replace it.

Also inspect for bent valves and push rods.

Thanks for clearing that up for me, I get what you're saying now. My only question is would one bad lobe on the cam shaft effect 3 cylinders?

Thanks again for your time and expertise,
Joseph~

[quote:465522a9e3="jfarrell305"]Thanks for clearing that up for me, I get what you're saying now. My only question is would one bad lobe on the cam shaft effect 3 cylinders?

Thanks again for your time and expertise,
Joseph~[/quote:465522a9e3]

Joe

I overlook something here-okay When you pull the head did you change the H/gasket those cyls is in the middle adjacent to each other-am hinting on blown gasket/warped head and no am not ready to say crack block.

Check for bent push rod/collapsed lifters-as for the cam no one bad lobe will not take out 2 more cyls.

Comeback and tell me what's happening.

[quote:980e7aafa4="rasmataz"]
Check for bent push rod/collapsed lifters-as for the cam no one bad lobe will not take out 2 more cyls.

Comeback and tell me what's happening.[/quote:980e7aafa4]

I checked the push rods and lifters as according to my Chiltons's and everything seems ok with them. The old gasket does not appear to be blown though I do have a new one ready to install when i get back to that point.

As for the warped head, I think I would need to take it to a machine shop to verify that. But if a warped head were causing my problem wouldn't at least part of the gasket be blown out?

I was thinking about installing the new gasket and putting the motor back together just enough to do another compression test... but I fear this may just be wishful thinking on my part. Think it's worth a shot?

[quote:7de62a7af7="jfarrell305"][quote:7de62a7af7="rasmataz"]
Check for bent push rod/collapsed lifters-as for the cam no one bad lobe will not take out 2 more cyls.

Comeback and tell me what's happening.[/quote:7de62a7af7]

I checked the push rods and lifters as according to my Chiltons's and everything seems ok with them. The old gasket does not appear to be blown though I do have a new one ready to install when i get back to that point.

As for the warped head, I think I would need to take it to a machine shop to verify that. But if a warped head were causing my problem wouldn't at least part of the gasket be blown out?

I was thinking about installing the new gasket and putting the motor back together just enough to do another compression test... but I fear this may just be wishful thinking on my part. Think it's worth a shot?[/quote:7de62a7af7]

Go for it-you only die once- it is not neccessary for the gasket to burn thru.its expansion that's doing it.