Broken Crank?…spun bearing?

[Flyingpiper59]

My 27 T started knocking horribly today…..the oil level was optimum……wasn’t pulling a hill or under a load….just came out of nowhere…wasn’t overheated….was a mile from home and limped it back….I’m guessing a rebuild is on deck!…… I’ve rebuilt many old Ford tractor engines, but being new to the model T, I understand that these rebuilds are different because of the Babbit bearings and other considerations……….and they much more specialty project…..any input on the best way to move forward would be most welcome….I’m located in rural PA…..two hours above Williamsport

[Gracie'sDad]

You have my condolences. I will say from experience that if you had broken your crank you would not have been able to limp to anywhere. Best of luck.

[jiminbartow]

This is just a shot in the dark question, but Is it possible for you to “spin” a poured babbited bearing? Unlike newer cars with drop in bearings, babbit is pretty much anchored to the bearing bed. Jim Patrick

[Joe Reid]

What does acting horribly mean? How about broken springs on brake shoes and shoes floating around in the drum?

[Flyingpiper59]

Sorry Joe, I must have not been clear….the engine was knocking badly

[Joe Reid]

Timer issues? Lots of things affect the engine. If you think it is a bearing, drain the oil, remove the bottom cover and check it out. If it is a bearing issue there will be babbit in the pan and probably play on your connecting rods and crank. I thought I had a transmission issue but what the real problem was rear end thrust washers dissolved. The entire drive train makes noise. Popped the brakes because of play.

[Wayne Sheldon]

This is just a shot in the dark question, but Is it possible for you to “spin” a poured babbited bearing? Unlike newer cars with drop in bearings, babbit is pretty much anchored to the bearing bed. Jim Patrick

Definitely yes! If the rod or block is not properly cleaned and tinned, Babbitt bearings can and do break loose and spin! Usually, the Babbitt will break up and fall out in pieces very quickly. It can also hammer out into bizarre ribbon shapes! I have seen that a couple times! One engine I pulled apart (I had bought it to rebuild), had one bearing rotated about ninety degrees! That one hadn't hammered apart yet, although it was loose enough to knock badly, but was interesting to look at!

[Allan]

If the inspection plate is removed from the bottom of the pan, you will be able to see if a rod has run a bearing. The good news is these can be replaced in the car without even pulling the head. Have a look and see what you can find before tearing in to it.

Allan from down under.

[Thorlick]

I had that happen to my 1927 last week. It was such a convincing knock that, combined with mag, starter and generator issues, I pulled the engine out.

I quickly found that the lack of power and sudden knocking turned out to be a blown head gasket. It is worth either a compression test or pull the head off first.

My gasket blew between #1 and #2. I found the deck was ok but the aluminum Z head is warped. .008” between 1 and 2, 2 and 3, 3 and 4. It is going to the machine shop tomorrow to get decked flat… again!

Head gasket “knock”

It’s easy to check for this problem before pulling the engine if there is no other problem.

The obvious thing I heard but didn’t understand was the “knock” was loudest near the muffler!

The knock was so convincing I checked all 4 rod bearings (all perfect) before finding the head gasket problem!



IMHO, TH

[Joe Bell]

Before you do any thing find where the knock is coming from, take a good screw driver with insulated handle and ground out each spark plug, if the knock goes away at no. 1 plug then you know where to look first, if it get quieter on 2 & 3 then center main is out if it gets quieter on no.4 then you know it is no.4 to look at. This is how I have tested where to look for years, if there is no change when you ground it out on running then you know it is a dead cylinder. Hope this helps!

[TXGOAT2]

"Before you do anything find where the knock is coming from..."

Amen to that. If you don't have a Model T Service manual, get one, and read the section on diagnosing engine knocks. A knock could be a number of different problems, including hub/brake troubles, as mentioned, the U-joint, problems with the timer wire loom, various internal engine problems, and more. Many problems which cause sudden knocks can be repaired without much difficulty or expense. But the first step is to find out exactly what the problem is.

[John kuehn]

Absolutely! Try to diagnose where the knock is coming from before pulling the engine, tearing it down all over the floor and then wondering what happened!
It’s a tendency to do that when a noise is heard in the engine.
Do as Joe Bell says as that’s a time proved method using a screwdriver to locate a knock.

On a T you can’t pull the engine every time you hear a noise or knock and most of the time you don’t need to.

If your new to T’s read and study the Ford service manual to find out what you DONT DO when working on a T. You’ll be glad you did! It can save you a lot of unnecessary headaches.

[Norman Kling]

A few questions about the knock.
1. Is it loudest when the engine is cold?
2. Is it loudest when accelerating?
3. Is it loudest when you are just going along at an even speed, maybe when just slowing very slightly?
4. Are there any conditions where it does not knock at all?
5. Does it knock at idle ?
6. Does the position of the spark lever affect the knock?
A test by shorting out the plugs one at a time will help you find the area. Also a Piece of plastic pipe listening to various points on the engine help Especially at the front where the timing gear is, also the center main and rear of the block. Then on top of the head next to each cylinder.
Some "knocks" are loud clicks caused by loose valve clearances which can happen with adjustable lifters. Other knocks are loud clunks, and others are like a loud rattle. Even some noises from the rear axle can be transmitted up the tube toward the engine.
So please answer some of these questions and we might be more likely to help you diagnose the cause. Also if you are a member of a local club, you might inquire if there is someone in your area who could help you.
Norm

[TRDxB2]

My 27 T started knocking horribly today…..the oil level was optimum……wasn’t pulling a hill or under a load….just came out of nowhere…wasn’t overheated….was a mile from home and limped it back….I’m guessing a rebuild is on deck!…… I’ve rebuilt many old Ford tractor engines, but being new to the model T, I understand that these rebuilds are different because of the Babbit bearings and other considerations……….and they much more specialty project…..any input on the best way to move forward would be most welcome….I’m located in rural PA…..two hours above Williamsport

I was told many years ago not to diagnose or to suggest a repair to the auto-mechanic when I brought the car to fix a problem. Doing so could lead to an unnecessary repair plus what was needed.

So when you started to say "My 27 T started knocking horribly today…" the word knocking could refer to the traditional use of the word, that is a fuel issue (detonation) rather than a broken this or that. So as Norman is suggesting a more descriptive account is needed to remove any ambiguity. Also, as suggested, removing the transmission inspection plate for a look see can narrow down possibilities or identify them quickly.

[Jerry VanOoteghem]

Everything is total guesswork and a waste of time until you remove the inspection cover and have a look inside. Let us know what you find there.

[Craig Leach]

Defiantly fallow these guys advice! The worst knock I ever had was the homemade scoop for a high volume front oiler came off. Sounded like all four rods came apart. Shut it off & trailered it home. Spent days trying to find the knock, eliminated rods, mains, wristpins, pistons, valves. Took the trans cover off after thinking I might have broke something in the trans. (I do not run a mag in this engine so I knew it was not a magnet came apart)
While looking around in the trans with a bore camera I spotted something that didn't belong. What I found was the scoop ripped in two pieces and wadded up onto balls. 3 hours of fishing with a Mac bendy magnet and they where out through the starter hole. Flushed it with a quick oil change.
The inspection covers & starter where the only things I had to take off & I was ready to pull the engine as the first step so do look first.
Craig.

[Dan Haynes]

"If the inspection plate is removed from the bottom of the pan, you will be able to see if a rod has run a bearing. The good news is these can be replaced in the car without even pulling the head."

Replace a rod bearing without pulling the head? This is a trick I need to learn!

[pron022020]

"If the inspection plate is removed from the bottom of the pan, you will be able to see if a rod has run a bearing. The good news is these can be replaced in the car without even pulling the head."

Replace a rod bearing without pulling the head? This is a trick I need to learn!

Yeah you cut the rod in half and weld it back together after rebabbitting it!!

[Scott_Conger]

Or, you pull the piston down far enough to pull the wrist pin and drop the rod.

Not my method, but it's been done.

[speedytinc]

Or, you pull the piston down far enough to pull the wrist pin and drop the rod.

Not my method, but it's been done.

Been there, done that on a road trip.

I recently replaced a crank without pulling the head. It was not necessary to pull the head.
Head gaskets are too scarce to waste.

[Erik Barrett]

It is in fact possible to change a rod without pulling the head. Many years ago I lost a rod bearing on the tour associated with the Bakersfield swap meet. When we got it back I went shopping at the meet and found a serviceable rod. Dad told me how he and a friend did it years ago. Slide the piston down far enough to remove the wrist pin and the rod will come out. The car had a Rajo head and pulling it off wasn’t really an option that would work at the time. I had quite a crowd watching the job happening. It worked but not for the long term. Turns out I had a cracked low drum that was shredding the band lining and clogged the internal oil tube. The accessory oiling lines would supply enough to let me drive around on flat ground but as soon as I worked the engine hard on a grade they were insufficient and a rod would fail. That heavy 1926 Tudor would really walk the dog while it held together. In 2000 I bought it sight unseen off the classified page here on the MTFCA site. Dad and I got one way plane tickets and drove it home from Seattle to Sacramento in five days with zero issues. As soon as it got here it was nothing but trouble. They all have personalities.

[Norman Kling]

The rods can be replaced without pulling the head if you have more modern pistons with all the rings above the wrist pin. Be very careful not to let the bottom ring slide past the bottom of the cylinder or you will have a problem such as I had.
Norm

[Wayne Sheldon]

I too have successfully changed a rod out the bottom by pulling the piston down. It was great fun! Era cast iron piston with a ring near the bottom, in cylinder number one. Changing the rod was easy. Getting the bottom ring compressed to go back up? Not so much.

HOWEVER!!!!!

Not all blocks are exactly alike!
I later tried to change a rod the same way, also number one. This time, there was just enough difference in the block casting that the piston wouldn't go quite far enough down. And the wrist pin could NOT push to the side enough to release the rod.

I fought that thing for an hour before I gave up and pulled the head. No twist or turn or push could move the pin quite enough. The worst part was the lower ring again had popped out, and fight it as I could, did NOT want to compress and go back up!

[Luke]

If you do drop the piston down far enough to let a ring escape it's easy to deal with ... simply use a jubilee clip to compress the ring and push the assembly back up.

Luke.

[speedytinc]

If you do drop the piston down far enough to let a ring escape it's easy to deal with ... simply use a jubilee clip to compress the ring and push the assembly back up.

Luke.

What is a jubilee clip? I have used a worm drive hose clamp or 3 put together due to need in the field.
Its no fun, but you do what you got to to get home.

[SteveD]

Jubilee is a brand name for a worm drive hose clamp.

[Allan]

I have done two now. The first was in Henrietta, and I didn't want to disturb her crusty appearance any more than I had to. No 1 rod was replaced with a used equivalent, scraped and timesaver lapped. We did have moments getting the bottom ring up the bore, but doing all the work on a hoist made it all much easier to manage.
The second more recent one was on an engine on a stand in the workshop. The paucity of head gaskets made us do this number 4 rod without pulling the head. The bearing had been poorly tinned and had shed a few chunks from one side. This was discovered when fitting a starter flywheel to the unit. The bearings and crankshaft grind were recent, so I sent the rod away for remetalling, and had it back from interstate in 6 days, thanks to Frank.
This piston had replacement rings, the bottom one being grooved around the circumference. A twitch of copper wire compressed it nicely and up she went.
This car is being rushed through to have it ready for a national tour at the end of September, so a complete teardown to check other work was not going to fit the time schedule.

Allan from down under.

[Flyingpiper59]

Thanks Alan….. This is going to be new to me, I’ve put in connecting rod bearings in scores of 30s and 40s Ford tractor engines but this model Tis going to be a new experience for me…. Research on deck for this one