Need some advice on a low pressure 47 Cub

Farmall Cub Forum -- Questions and answers to all of your Cub related issues.

Moderator: Team Cub

Forum rules
Notice: For sale and wanted posts are not allowed in this forum. Please use our free classifieds or one of our site sponsors for your tractor and parts needs.
B52
Posts: 14
Joined: Fri Sep 30, 2016 12:24 pm
Zip Code: 55956

Need some advice on a low pressure 47 Cub

Postby B52 » Sun Mar 18, 2018 9:40 pm

Good evening all. I’m in need of some help with my 47 Cub restoration project.
My son and I were making some pretty good progress on this project until we did something really stupid!
We are both pretty green at restoring tractors in general, but it sounded like fun…at the time.
Progress was good early on. We tore down the entire tractor and engine. Sent out the engine to have the valves and valve guides replaced. Valve seats were ground and bearings replaced. New rings and cylinders de-glazed.
By September we got it all put back together and were ready for the ‘fire-up’.
We attached a temp gas tank and poured in water since we were planning on tearing it down right after ‘start up’ to do the final paint on it.
It initially started but ran at full throttle. We couldn’t get it to idle down so we shut it down. Turns out the gasket on the carburetor was the wrong thickness and the butterfly valve was getting stuck in the manifold.
After that we couldn’t seem to get the old girl fired up again and we let it sit for a while. That’s when we made our big mistake.

WE LEFT IT FULL OF WATER!!!!!

Did I mention we’re from the upper Midwest?
By the time we realized our blunder it was almost Thanksgiving! Even though the cub was in a closed garage it still got plenty cold out there and the damage was done. The front radiator housing had cracked and the fins on the radiator had bulged out!
I checked the head and the block but didn’t find any additional damage.
After I repaired the housing and replaced the radiator we poured in antifreeze to see if we could find any additional leaks. Nothing from the outside. So here’s where it stands and here’s my problem.
I can’t seem to build up enough pressure in the cylinders. All four come in at or around 40 60 psi.
I’ve replaced the head gasket and had the head checked for cracks and warps. Head came in good.
I’ve checked the valve settings, they needed some adjustment, but it didn’t change the psi amount.
I don’t know where the coolant level typically sits inside the engines water jacket. Could it be possible that I cracked the cylinder walls from within? And if so, would it be possible to crack all four? (Remember, all four cylinders have a psi reading of 40 to 60 psi).
Something worth noting. When we came out to the garage after the freeze damage, we noticed that a fair amount of water flowed out for the large crack in the radiator housing. So perhaps the majority of the unfrozen water still in the block spilled out once it had somewhere to go.
Is there a way to check if the cylinders are damaged internally without tearing the engine completely down again?
What else could be causing the low psi measurements?

Thanks for any advice you can offer me…..
But please don’t advise me to take up needle point.

I know this was a stupid mistake, but we all need to make them in order to learn.

User avatar
RaymondDurban
Cub Pro
Cub Pro
Posts: 4417
Joined: Wed Dec 26, 2007 7:45 pm
Zip Code: 32536
Circle of Safety: Y
Location: FL, Crestview

Re: Need some advice on a low pressure 47 Cub

Postby RaymondDurban » Sun Mar 18, 2018 9:49 pm

Very unlikely the cylinders cracked.
With all four spark plugs removed, add a tablespoon of oil to each cylinder and recheck you compression results turning the engine with the starter for a couple revolutions.
An easy check for internal leaks (compression leaking into the water jacket) is to fill the water all the way to the top and attempt to crank the engine. If compression is leaking, bubbles will rise to the fill neck of the radiator.

B52
Posts: 14
Joined: Fri Sep 30, 2016 12:24 pm
Zip Code: 55956

Re: Need some advice on a low pressure 47 Cub

Postby B52 » Sun Mar 18, 2018 11:14 pm

Thank you very much for the advice! I will try that tomorrow when I get home from work.

If I DO find bubbles in the neck of the radiator what would that most likely tell me?
- The block is cracked or
-my head gasket is blown?
or possibly both?

tst
5+ Years
5+ Years
Posts: 2818
Joined: Tue Jan 12, 2010 2:08 pm
Zip Code: 12514
Circle of Safety: Y

Re: Need some advice on a low pressure 47 Cub

Postby tst » Mon Mar 19, 2018 7:11 am

40-60 lbs of compression is very poor, the least it should be is 85-90 lbs, a real good motor over a hundred lbs easily, hard to start with that low compression

Eugene
Team Cub Mentor
Team Cub Mentor
Posts: 16880
Joined: Fri Jul 02, 2004 9:52 pm
Zip Code: 65051
Circle of Safety: Y
Location: Mo. Linn

Re: Need some advice on a low pressure 47 Cub

Postby Eugene » Mon Mar 19, 2018 7:27 am

Have you double checked the valve tappet gap?
I have an excuse. CRS.

User avatar
gitractorman
10+ Years
10+ Years
Posts: 2591
Joined: Mon Oct 24, 2005 11:35 am
Zip Code: 14072
eBay ID: toysforjake
Tractors Owned: Lots of Cub Cadets!
1951 Farmall Cub
1977 IH Cub
1966 IH Cub
1965 IH Lo Boy
1964 IH Lo Boy
1949 Farmall Cub
Several IH 154 Lo Boys
1979 IH 184 Lo Boy
Simplicity 4416 Sovereign
Simplicity Conquest
Simplicity Legacy 4x4 Diesel
Mitsubishi MT180D 4x4 Diesel
Circle of Safety: Y
Location: Grand Island, NY

Re: Need some advice on a low pressure 47 Cub

Postby gitractorman » Mon Mar 19, 2018 7:44 am

It's unlikely that the cylinder walls cracked. Also, since the compression is nearly identical on all cylinders, it further supports this.

I would guess that the valves are not adjusted correctly, or worst case, the piston rings are shot from being started up and run at wide open throttle before the rings had time to break in, then shut down and sat for so long. They may have even rusted some in that time just due to condensation over the winter. Since everything was new, honed, clean, it's much more likely that things rusted up while sitting. New engines are rarely run one time "really fast and hot" then shut down for months, so I'm leaning this direction.

Before running, did you prime the oil pump???? If not, the engine likely ran most of the time you described without ANY oil getting to the cylinders.

When you pulled the head, did you look around in the cylinders to inspect anything? Did you turn the engine over by hand to see the pistons move, valves open close, etc? After being run the way you describe, it should have been inspected thoroughly, especially while the head was off.
Cub Cadets 682, 1811, 1864, Simplicity Legacy XL 4x4 Diesel with FEL, 60" mower, 50" Tiller

B52
Posts: 14
Joined: Fri Sep 30, 2016 12:24 pm
Zip Code: 55956

Re: Need some advice on a low pressure 47 Cub

Postby B52 » Mon Mar 19, 2018 8:51 am

Thank you all for your responses and suggestions! Here are some answers to the questions.
Q: Double check the tappets
A: Yes, with the cover off I watched all of the valves move. Nothing stuck. checked the gap again 0.013 (cold).
Q: Shot piston rings.
A: Haven't thought about that....
Q: Priming the oil pump.
A: Yes, I was very concerned about this. I read a post somewhere on how to do this correctly and I made absolutely sure that the engine was well primed.
Q: Inspection of the cylinder after pulling the head.
A: Yes, I inspected all four cylinders and everything looked good. I didn't see any signs of rust. I pull a tablespoon of oil in each cylinder and let it sit for a while. nothing leaked through.

B52
Posts: 14
Joined: Fri Sep 30, 2016 12:24 pm
Zip Code: 55956

Re: Need some advice on a low pressure 47 Cub

Postby B52 » Mon Mar 19, 2018 9:02 am

Here's one of my thoughts. Please tell me if I'm out in "left field" with this.
When I sent the engine out to the machine shop they had to pull the crank to replace the mains.
Could it be possible that they did not line up the crank, timing and governor sprockets with the punch marks?
Since the engine actually ran for about a minute I've dismissed this theory, but the thought keeps coming back to me.

If my valves and seats and gap are set correctly I can't explain why I'm losing compression.

I'm leaning more towards bad rings at this point (or a bad head gasket) now since all four cylinders come in at 40 to 60 psi.
That's some pretty bad compression, but it's CONSISTANTLY bad if you know what I mean.

By the way, this site has been extremely helpful to me. Thanks again to everyone for your help and great advice!

I really appreciate it!

tst
5+ Years
5+ Years
Posts: 2818
Joined: Tue Jan 12, 2010 2:08 pm
Zip Code: 12514
Circle of Safety: Y

Re: Need some advice on a low pressure 47 Cub

Postby tst » Mon Mar 19, 2018 9:56 am

to determine rings or valve problem do a compression check 1st, after doing a cylinder adding a teaspoon of oil to that cylinder and test again, if the #s go up bad rings or excessive cylinder wear, if #s do not change bad valves, or if you have a air source you can use an adapter to put air in a cylinder, if air is blowing back through the oil filler bad rings or excessive cylinder wear, air blowing out the carb or exhaust is bad valves

Crimson Tim
Cub Star!!
Cub Star!!
Posts: 252
Joined: Wed Feb 19, 2014 1:09 pm
Zip Code: 32736
Tractors Owned: The crew:
"John", 1952 Cub
"Paul", 1951 Cub
"George", 1958 LoBoy Cub with Wagner 45 Loader
"Ringo", 1977 Cub

So far, Paul and Ringo have arrived. John and George will follow in a few weeks.
Circle of Safety: Y

Re: Need some advice on a low pressure 47 Cub

Postby Crimson Tim » Mon Mar 19, 2018 1:04 pm

Another thing to check when all cylinders come up with consistent, but unexplainable low compression: bad gauge?
Maybe the no-start is for an entirely different reason. Fuel and electrical gremlins can easily crop up when it’s been sitting for a while.
Do you have access to another gauge to try, or another known-good engine to try this gauge on?

User avatar
ricky racer
10+ Years
10+ Years
Posts: 4266
Joined: Wed Sep 12, 2007 8:40 pm
Zip Code: 49120
Circle of Safety: Y
Location: Niles / Buchanan, Michigan

Re: Need some advice on a low pressure 47 Cub

Postby ricky racer » Mon Mar 19, 2018 2:55 pm

Do you know what kind of end gap the rings had after de-glazing? What about piston fit? A 60 year old tractor likely needed more than de-glazing...
1929 Farmall Regular
1935 John Deere B
1937 John Deere A
1941 John Deere H
1952 John Deere B
1953 Farmall Cub

B52
Posts: 14
Joined: Fri Sep 30, 2016 12:24 pm
Zip Code: 55956

Re: Need some advice on a low pressure 47 Cub

Postby B52 » Tue Mar 20, 2018 10:19 pm

Good evening all,
Here's a follow up on the 47.
1. As per RaymondDurban's advice I filled the radiator to the neck and cranked the tractor over. Lucky for me NO BUBBLES! Thanks for the tip Ray.
2. As many advised, I reset all of the valve gaps.(0.013, not much to re-set, but I did it anyway). Rechecked my compression and my readings were; #1=30lbs. #2=50lbs. #3=50lbs. and #4=50lbs. Not much change here.
3. A side note: while my son and I were cranking the engine over we could hear hissing from the valve area. Assuming it was just air being sucked from the carburetor or air leaving the exhaust.
So I place one of my hand on the intake of the carb and my other hand over the exhaust.
intake.jpg

I can feel suction from the carburetor end but I can also feel suction from the exhaust manifold!

Why would there be suction coming from the exhaust manifold??

Thanks for your advice in advance.

B52

B52
Posts: 14
Joined: Fri Sep 30, 2016 12:24 pm
Zip Code: 55956

Re: Need some advice on a low pressure 47 Cub

Postby B52 » Tue Mar 20, 2018 10:25 pm

Crimson Tim wrote:Another thing to check when all cylinders come up with consistent, but unexplainable low compression: bad gauge?
Maybe the no-start is for an entirely different reason. Fuel and electrical gremlins can easily crop up when it’s been sitting for a while.
Do you have access to another gauge to try, or another known-good engine to try this gauge on?


I did check a compression gauge out from the local auto parts store because I thought my gauge was no good. Unfortunately I got the same results with the auto parts store gauge.

B52
Posts: 14
Joined: Fri Sep 30, 2016 12:24 pm
Zip Code: 55956

Re: Need some advice on a low pressure 47 Cub

Postby B52 » Tue Mar 20, 2018 10:34 pm

ricky racer wrote:Do you know what kind of end gap the rings had after de-glazing? What about piston fit? A 60 year old tractor likely needed more than de-glazing...

I do not know what the end gap of the rings were.
They were all replaced when I sent the engine to the machine shop.
If memory serves I think the machinist said the pistons and cylinders were fair, but not great. He gave me the option to bore them out and oversize the pistons, but I opted not to. I may regret that decision now.

Matt Kirsch
10+ Years
10+ Years
Posts: 4578
Joined: Tue Jun 08, 2004 3:04 pm
Zip Code: 14559
Circle of Safety: Y
Location: Rochester, NY

Re: Need some advice on a low pressure 47 Cub

Postby Matt Kirsch » Wed Mar 21, 2018 10:44 am

Suction from the exhaust manifold means your exhaust valves aren't closing.


  • Similar Topics
    Replies
    Views
    Last post

Return to “Farmall Cub”

Who is online

Users browsing this forum: No registered users and 4 guests