Engine Knock

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Apis Mellifera
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Engine Knock

Post by Apis Mellifera » Mon Jun 27, 2022 3:51 pm

After finally getting my '22 running well and building a Touring body so my wife and kids can all go for a ride, on the first trip around town, the engine suddenly started making a loud knocking sound while cruising in high gear on a flat road. The knock (banging more accurately) increases with load. At idle it gets more pronounced as the throttle and advance increase. I'm thinking rod knock, though I've never had it develop suddenly. I used a short broom handle as a sounding stick and the noise seems to be low in the center of the engine. I let it sit for two days to cool off and started it this morning - knock is still there. I just paid nearly $1000 for a new radiator and the $250 alternator I order for it before the failure arrived in the mail today.

Any ideas or likely culprits? I've owned this Model T since this spring and it's my first experience with one. It's not gone well. I'm thinking of bailing on this thing unless there's a repair that's cheap and doesn't pull the engine out.

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TRDxB2
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Re: Engine Knock

Post by TRDxB2 » Mon Jun 27, 2022 4:13 pm

Everything is a guess -drain the oil and remove the inspection pan plate to see whats there, or not
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Re: Engine Knock

Post by Jerry VanOoteghem » Mon Jun 27, 2022 4:16 pm

As Frank says, you've got to have a peek inside.


Norman Kling
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Re: Engine Knock

Post by Norman Kling » Mon Jun 27, 2022 4:18 pm

A connecting rod knock is usually more pronounced when running along at a constant speed neither accelerating nor decelerating but on flat ground or going slightly downhill but not slowing in compression. A piston slap or a main bearing knock is usually more pronounced when accelerating or pulling an uphill grade.
Try pushing up the spark lever slightly as your engine is knocking. if it still knocks move it up a little more. If this stops the knocking, your problem might just be caused by driving with the spark advanced too far.

Another possible cause of a knock might be if the engine block has been bored quite large oversize, the top of one of the pistons might be hitting the head at the edge of the cylinder.


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Re: Engine Knock

Post by John kuehn » Mon Jun 27, 2022 4:24 pm

Sounds like a rod but pull the pan cover and tap on each rod or try to move them up and down.
If not a rod a wrist pin or? Good luck and hope it’s something that can fixed with engine in the car.
A transmission drum can be cracked for a good while before it goes. Might be a good idea to look inside the transmission too.

Remember when driving a T try not to push it. Running around 30-40 is fast enough in a Model T. As others stated advancing the spark will cause a knock. An average speed of around 30 will help your T to last longer.


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Re: Engine Knock

Post by speedytinc » Mon Jun 27, 2022 4:45 pm

New Babbitt motor, or old & unknown?. Old Babbitt can get brittle & crystallize & crumble away. That accounts for the "all of a sudden".
The other all of a sudden is running out of oil & a melt out of the Babbitt.

"Get out & get under" Pull the inspection cover. Sorry for your loss.

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Craig Leach
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Re: Engine Knock

Post by Craig Leach » Mon Jun 27, 2022 5:02 pm

Hi Matt,
Everyone is correct on this, a inspection cover gasket is cheep. If it's not apparent what the issue is get someone to hand crank the engine over for you so you can see things you can't feel. If you have aluminum pistons it's possible to change #1.2.&3 rods on a three dip pan ( #4 is pretty challenging ) a 4 dip pan is easier. With out pulling the head, Since head gaskets seem to be made from unobtainium now. If you have cast iron pistons it's a lot more difficult because you will need to drop the bottom ring out of the bore to get the wrist pin out.
Good Luck.
Craig


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Apis Mellifera
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Re: Engine Knock

Post by Apis Mellifera » Mon Jun 27, 2022 6:57 pm

Many thanks for comments. I pulled the cover off and immediately found a lot of bearing material. See pics. The big end of rod #1 was clearly the source. My son rotated the engine while I inspected the others and they seem fine. Pistons appear to be iron. I pulled the cap and there is a very thin layer of babbitt still holding on. This might explain the nearly pristine rod journal. There is very light, normal wear. No scoring and no heat bluing. A fingernail glides across it unfettered. It measures 1.246" Aside from some concern for the condition of the other bearings, am I wrong in thinking I can scrounge a replacement rod and carry on? We may get in some family drives this summer after all. Of course, the head gasket might be a problem.
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Topic author
Apis Mellifera
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Re: Engine Knock

Post by Apis Mellifera » Mon Jun 27, 2022 7:02 pm

I should also say that this car (and Model Ts in general) is unfamiliar to me. I assume it is old babbitt. The pieces are mostly small crumbly bits. As seem in the pic, there are some larger pieces with a radius that appear to be a thrust surface on the sides of the rod.


TXGOAT2
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Re: Engine Knock

Post by TXGOAT2 » Mon Jun 27, 2022 8:30 pm

The crank pin needs to be carefully checked with a micrometer. They tend to get out of round, and out of round and taper need to be checked for carefully. It's also important to get as much debris out of the engine as possible. A newly-re-babbited rod that is fitted correctly may get you by, if the crankpin checks out good. Another thing to consider is that your oil pipe may be clogged, which is a possible cause of the rod bearing failing. Another possibility is that, after the bearing failed, the loose rod allowed the piston to hit the cylinder head, which may have pinched the top ring groove or cracked the ring or ring land.


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Re: Engine Knock

Post by John kuehn » Mon Jun 27, 2022 8:47 pm

I put together a T engine that still had good main babbit and put some good used rods that had slightly worn rod bearing surfaces on them. That was several years ago when I first got interested in T’s and built the engine from what a older friend called “good used parts” so I proved to myself it could be done.

It ran well for several years until I rebuilt it later.

Some will frown doing it that but there are T’s running around that have been built up that way.
Of course it’s best to go through the engine and have new mains poured in it and buy some new rods and etc.

It would be a learning experience to pull the head and install new rings and piston pins and bushings in them if it requires them. You can check out the other rods if you want. Just a suggestion but it could run and probably be OK for a good while doing it that way. You would need to pull the head anyway regardless if you try to fix it yourself or pull the engine for more work. If it just started knocking the rod journal may not be out of round to bad. Mike it to be sure.

The alternative is a engine rebuild which would be at 2000.00 at least if you did it your self. Having it done it would closer to 4-5,000.


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Re: Engine Knock

Post by Norman Kling » Mon Jun 27, 2022 9:10 pm

Hopefully it is only the one rod bearing which is worn out and the crankshaft is still within limits. You should check them all. Number 4 is very hard to get to the rod bearing, but can be done with patience. If it is only number 1 which is bad, you might be able to replace it without removing the head. I have seen it done, but had no luck when I tried to do it on one of mine. The best way to replace it is to remove the head and pull out the piston and rod to replace it. At this time head gaskets are unavailable so you might have a long wait to fix it. You should as noted above check the oil line because if it is clogged, you will get no oil to the front of the engine. I like to have an auxiliary oil line on mine just in case.
Norm

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Re: Engine Knock

Post by JTT3 » Mon Jun 27, 2022 9:38 pm

Matt, other members may frown on this but I have done this in a pinch. First, is the babbitt in the rod itself in decent shape? If so then second, do you have access to any good used rod caps? If so you may be able to get by for now (summer months) with fitting a good used cap on the rod. The caveat is the cap needs to have enough good babbitt that you will be able to fit some shims in between the rod & cap. It’d be even better if you had some yellow time saver. I suppose many folks have done this “ in a pinch”. If you have fellow T model friends close by they may have extra caps you can buy and give it a try. It may last forever or it could give you a few days. This is just a temporary fix so you can enjoy a few more days, weeks…. driving your T. If it works start saving your money to refresh or rebuild your block. I guess now I’ll be the official spear catcher for a bit but I can tell you that on a trip with other folks my Tudor had basically the same situation and that temporary fix lasted years. Probably not the wisest choice but one that did work for me. My mentor once used a piece of leather to make it home when he had a similar issue. Back in the day when money was really tight they did what they could to get by for a bit. That truly is the beauty of the model T, they are very forgiving even for cheapskates like me.
Good luck, Best John

PS , tighten all the rods & mains while you’ve got it opened up.
Last edited by JTT3 on Mon Jun 27, 2022 10:54 pm, edited 1 time in total.


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Re: Engine Knock

Post by John kuehn » Mon Jun 27, 2022 10:10 pm

As far as T head gaskets are concerned copper head gaskets are currently unavailable but the engine overhaul gaskets sets that are Fel-Pro brand are available at Auto-Zone by special order from their supply house. Their sets have the conventional head gaskets that aren’t copper and do work. It’s not necessary to use copper but purists do like to.
Fel Pro part no. FS 7012B for around 160.00 for the engine gasket set. You can call Auto Zone
or another auto parts dealer that handles Fel Pro brand products to see if they can get a set.

Good luck.

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Re: Engine Knock

Post by Craig Leach » Tue Jun 28, 2022 2:35 am

Matt & John T,
I'll volunteer for some of those spears too. My first T is a speedster I ran a used engine that I was told to rebuild before I used it! I got over 7 years 16 speedster runs & many tours on it before I broke a low drum and had to remove it. In that time I replaced the valves & lifters, one head ( valve broke the head instead of the piston) two rods & the bands. the rod journals where over .001 out of round and had to be adjusted every 3 -5 Hundred miles depending on how hard I ran it.
( and I ran it between real hard & super hard) Some where I missed the class on Model T's aren't supposed to go 55MPH+. I'm still running that engine after a crank regrind rebabitted rods & main caps refreshed rings, valves & a complete trany rebuild. So Matt all may not be lost. Wish you all the luck in the world.
Craig.

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Re: Engine Knock

Post by TRDxB2 » Tue Jun 28, 2022 10:06 am

Best prices. Discounts on first order as well as order totals. NOTE FREE SHIPPING
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The past is a great place and I don't want to erase it or to regret it, but I don't want to be its prisoner either.
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Re: Engine Knock

Post by John kuehn » Tue Jun 28, 2022 10:26 am

That’s good! I forgot about Summit and Jegs! And free shipping. Thanks for the update.


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Apis Mellifera
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Re: Engine Knock

Post by Apis Mellifera » Tue Jun 28, 2022 9:07 pm

I have decided to replace all the rods since I'm in the engine anyway. And while I'm at it, I plan to replace the pistons with aluminum ones - probably high compression. Fortunately, the head gasket is copper and in good shape. Unfortunately, rod #3 is lightweight while the other three are heavy. The #3 rod cap was also drilled and a homemade X was cut in the babbitt.

If I understand correctly, no one will accept heavy rods as cores. Lang's does not have any rods in stock. They said Ron's was their supplier and was not producing consistently. They said Paul's (?) was another supplier, but they used inferior babbitt. Snyder's has only X'ed in stock, but will not ship until cores are sent in. I'd prefer non-X'ed, but something is better than nothing. Though I didn't ask, but I assume heavy rods would get rejected. So now I have to find three cheap, light rods, or a reconditioned set of four that do not require a core.

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Re: Engine Knock

Post by JTT3 » Tue Jun 28, 2022 9:34 pm

So Matt, just a few things. You need to check the crank journals on at least a 90 and make sure they are within tolerance. You also have to check clearance in each hole when you fit the pistons. I do 4-5 thou on aluminum pistons. I’d encourage you to hone the cylinders.


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Re: Engine Knock

Post by kmatt2 » Wed Jun 29, 2022 12:20 am

Matt, there is a lot to unpack in this long post. First measure the front three crankshaft rod pins both for out of round and taper front to back, pin four is harder to get to with the three dip pan. Check number four rod if you can, pack rags don’t drop anything. If crank pin is not to out of round or tapered then you have a chance with this engine. Next if the Babbitt is good in heavy rod two and four I would fit them first. Now you need 2 used heavy rods with good Babbitt, there are lots of these rods around. You could also just pay for core’s and get 4 re-babbitted light rods in the correct size, but they will need to be checked for fit. I wouldn’t change the pistons at this time unless there is a damaged one. While you are doing all this work check the valves and change if they are 2 piece valves. Clean that oil line and add a outside oil line. This should get your engine running well enough to drive at Model T speeds, 25 mph to 35 mph for this and next year. Then you can save up for rebuilding your engine and transmission as it needs. Good luck .


Topic author
Apis Mellifera
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Re: Engine Knock

Post by Apis Mellifera » Wed Jun 29, 2022 9:04 pm

In case anyone is in a bind for reconditioned rods in the future, Snyder's will accept heavy rods as cores. In fact, they are taking my haggard, mismatched set and are sending a rebabbitted, matched set in return.

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