Low compression in Cyl4, running a little hot. Took the head off, now what?

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration
Model T Ford Forum: Forum 2017: Low compression in Cyl4, running a little hot. Took the head off, now what?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Joe Fedullo, Milford MI on Sunday, July 09, 2017 - 11:47 am:

My '14 touring was running a little hot after long 35mph stints and after trying every other thing for overheating, (including soaking rad and engine in vinegar a few days, the Jelf method block flush with compressed air 3 times, checking fan and belt, checking timing, a brand new radiator, etc) I decided it was time to take the head off and clean out the coolant passages. Prior to doing so, a forum member suggested a compression check which showed cold:
Cyl 1 45PSI
Cyl 2 45PSI
Cyl 3 40PSI
Cyl 4 30PSI (I could hear compression leaking on this one)

I checked for bubbles in the radiator and found none while idling, so I proceeded to take the head off with the intent to clean the water passages and check the valves. Background info in this thread:

http://www.mtfca.com/discus/messages/708324/767150.html?1499006975

What I found surprised me. The head bolt that is in-between cylinders 3 and 4 was coated in carbon deposits. The 1/4" coolant passage in-between cylinders 3 and 4 was filled solid with black / brown material that when removed with a drill bit turned into fine dust.



I assume this means the head gasket was leaking, or there is a crack in that area. I inspected the head and block and could not find a crack, and when looking at the area between 3 and 4 the gasket looks a little darker, but not really blown. What are your thoughts?











(Message edited by 2slow on July 09, 2017)


Top of pagePrevious messageNext messageBottom of page Link to this message  By G.R.Cheshire on Sunday, July 09, 2017 - 12:03 pm:

It appears you didn't have as much clamping force between 3&4 and that may have been caused by the bolt hole not being cleaned out or the head bolt being a little too long due to torque stretch. I would have .010 shaved from the head. Don't let them put the head on a belt sander and call it good tell them you want it milled to ensure it is level. then check the deck for level


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Sunday, July 09, 2017 - 02:06 pm:

Joe

really appreciate your following up on this on this new post. Interesting to see what you found.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Sunday, July 09, 2017 - 02:42 pm:

I had similar problem from that same bolt on mine. The hole in the block was packed with junk. Apparently, I had managed to skip it when cleaning out the holes before installing my cylinder head. End result was the bolt was torquing to 50 ft-lbs but against the "bottom" of the hole and not squeezing the head to the block.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Sunday, July 09, 2017 - 03:07 pm:

Joe
I agree with Scott, thank you for the follow up posting.
It is something that I have not personally encountered, but it all makes logical sense to your symptoms. I'm glad it was not worse
All the best


Top of pagePrevious messageNext messageBottom of page Link to this message  By George n LakeOzark,Missourah on Sunday, July 09, 2017 - 03:08 pm:

When cleaning out the bolt holes on Derrick Pangs car, we didn't have the correct tap for cleaning. With a small flashlight and small thin screwdriver I twisted, scrapped,scrached all the crud out of the holes and we used new head bolts we got from Larry Blair. We got lucky, Derrick had a narrow vacuum attachment that got rid of all the grit, junk.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Joe Fedullo, Milford MI on Sunday, July 09, 2017 - 03:11 pm:

Because I was sure I heard the leak into a manifold I pulled Number 4's exhaust valve. It is magnetic (probably not stainless, but depends on the grade) and the stem measured 0.310 where unworn, and 0.3085 at the worst worn spot. It did show a little pitting in one area (picture is the worst spot)





Would you guys lap this valve and call it a day, replace it, replace them all, leave it alone?

Thanks,
-Joe


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Sunday, July 09, 2017 - 03:29 pm:

I'd look at the seat in the block and see how wide the seat is...probably too wide

I'd have the valve ground true again and recut the seat to match...but I have a NewWay cutter set and it would be quick and easy for me...

Perhaps for you, you could put just the tiniest dab of grind paste on the valve and kiss the seat and see where the pitting falls with respect to the actual seat. If it's in the seat, then you really ought to clean up the valve face and seat. It isn't that big of a job...the pitting will continue to get worse if it isn't seating and cooling.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Joe Fedullo, Milford MI on Sunday, July 09, 2017 - 03:55 pm:

So I put a little bit of grinding paste / lapping compound on the valve and very gently lapped it to find the seat. The seating surface is about 1/8" wide, and a couple of the pits are in the surface.

Debating what to do now...

-Joe


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Sunday, July 09, 2017 - 06:20 pm:

Did the seat completely clean up...? NO shiny spots left unlapped?

The seat surface is too wide, but you likely have 7 more just like it.

If everything cleaned up and you want to have fun quickly, I'd go with it.

Know though, that the valve(s) will not seal as tightly as possible and carbon bits may sometimes keep them from sealing well periodically. It could very well be that the lost compression in #4 and blowing sound was coming from #3 with that bad gasket.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Sunday, July 09, 2017 - 06:20 pm:

Joe, you'll have to make your mind up yourself. However, if you're anything like me: anything other than reaming up your valve guides one size, replacing all valves with new, and cutting all fresh seats, would annoy me and I'd think about that one valve every time I drove the car.

Ha! But that's just me. If you're on a budget (your shop photos do not suggest this to be an issue), then I'd say lap it and run it. If you're not really on a budget, just fix it where everything is correct and fresh and will run happily for years and years.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Sunday, July 09, 2017 - 06:22 pm:

when I said "seat", I meant in the block...that's where to check next...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Joe Fedullo, Milford MI on Sunday, July 09, 2017 - 07:15 pm:

Head cleaned up nicely, I sanded it with a flat block and some 320 grit oiled paper. It seems pretty flat when checked with a straight edge and a feeler gauge.



All the seats cleaned up well. No pits before lapping and no shiny spots after.

All of the exhaust valves had about 1/8" wide contact between the valve and the seat. I know it should be more like a sixteenth. I only pulled number 4's intake and it looked perfect so I did not lap it, just put it back together. The car / engine really do not have a lot of miles on a 90's restoration / rebuild.

Seth I am a bit like you, and am debating cutting new seats, changing all the valves, and while I am in there swapping out the iron pistons for aluminum ones with a new set of rings. (I found a couple of small vertical scratches in cyl#1 that are small enough I can't catch my finger nail on so they should come out with a hone.) It isn't the money, it is the time. My job keeps me busy and this would take the entire touring season if I took it on.

Although I feel it a little hackish, I am leaning towards just replacing the one exhaust valve. Would you guys replace just one valve (it would be different than the other 7) or run the one I have that has a few pits?

-Joe


Top of pagePrevious messageNext messageBottom of page Link to this message  By Philip Berg on Sunday, July 09, 2017 - 07:44 pm:

If you have the budget and tools replacing the valves isn't too complicated. I went through this a couple of months back on my 11 touring. Two piece original valves to one piece stainless. Didn't check compression prior to doing the valve change but my exhaust valves were ugly.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Philip Berg on Sunday, July 09, 2017 - 07:47 pm:

If you have the budget and tools replacing the valves isn't too complicated. I went through this a couple of months back on my 11 touring. Two piece original valves to one piece stainless. Didn't check compression prior to doing the valve change but my exhaust valves were ugly.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Sunday, July 09, 2017 - 07:55 pm:

This isn't two piece valves, they should work just fine for many miles. Put it together and have fun - that little pitting won't be noticed. Check the compression and do a full valve job next time it's getting lower again. (I would have lapped in all eight today, though )


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Sunday, July 09, 2017 - 08:08 pm:

I am with Roger. As you can see the head comes off with little trouble. Put it together, run it, have fun. Dig deeper when something else crops up (perhaps many years from now).


Add a Message


This is a private posting area. Only registered users and moderators may post messages here.
Username:  
Password:

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration