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Discussion Starter · #1 ·
I have a Sears Suburban 10 with a Tecumseh HH100 That I just rebuilt for the second time for the same reason. It would rattle at about 3/4 RPM. I got the crank ground .010 under and replaced the piston and honed the cylinder wall. When I put it back together at first there was not rattle, but over time it started to redevelop. (also I broke it in properly and changed the oil multiple times sae30) I discovered that if I decreased the point gap the rattle would quit completely, but it was really hard to start and kinda sluggish so I put the points back at .020. It rattles, but its not gotten any worse. It definitely not a knocking as it much quieter and not consistent at all. It doesn't change much under load. It gets quieter if anything. I know Tecumseh engines are notorious for this and I am wondering if this is a serious problem that needs addressed or a Tecumseh trademark that I don't really need to worry about. Any and all input is appreciated! I am really looking forward to snowblowing with this sears this winter and in my opinion it looks really good!
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Did you check or replace the crank bearings? Did you shim the race correctly? They will cause a knock. Doesn't quite sound like rod knock it almost has the higher pitch piston slap sound.

Crank bearings are usually overlooked but they do wear out especially the 2 piece bearings. Pull the flywheel and take the race retainer off. You will be able to see and feel a ridge on the race if it is worn out. The rollers in the bearing will be noticeably loose if they are worn but you will have to pull the crank back out to check both of them.

There is supposed to be only 0.001-0.007 crankshaft end play. Truthfully I like to see them rite around .002-.004 because it can tighten up a bit when the engine warms up. It can rattle a bit if there is more than .005-.007 especially if the bearings are worn a bit.

Here pages 40-43 shows you how to check and shim the crank.

Remove the shim gasket and metal sim if there is 1 and measure the clearance between the cap and the block. If there is no clearance between the cap and block? you will either have to buy a metal shim. The metal shim is .010” and the paper shim/gaskets come in thicknesses of .004/.005” and .005/.007”.

If you measure it and you get .005 between the cap and block then you have to add .007 worth of shim gaskets. If there is zero clearance then you have to add a .010 metal shim and then measure it again. If you add a .010 metal shim and you still have zero clearance between the cap and block? I suggest Replacing the bearings.

Tecumseh part number 32031 is the .010 metal shim. Shim Gaskets are Part numbers 31970 (0.003-0.004) 31971 (0.004-0.005) and 31972 (0.005-0.007)

Bearings and Races are Tecumseh part number 31932 for the bearings and 31928 for the races. You will need 2 of each if it needs new bearings. They are Timken or NTN National bearings and races depending on the year of the engine so you should be able to pull the part numbers off of them and get a set fairly easy. They are clearly marked.
 

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Discussion Starter · #3 · (Edited)
Did you check or replace the crank bearings? Did you shim the race correctly? They will cause a knock. Doesn't quite sound like rod knock it almost has the higher pitch piston slap sound.

Crank bearings are usually overlooked but they do wear out especially the 2 piece bearings. Pull the flywheel and take the race retainer off. You will be able to see and feel a ridge on the race if it is worn out. The rollers in the bearing will be noticeably loose if they are worn but you will have to pull the crank back out to check both of them.

There is supposed to be only 0.001-0.007 crankshaft end play. Truthfully I like to see them rite around .002-.004 because it can tighten up a bit when the engine warms up. It can rattle a bit if there is more than .005-.007 especially if the bearings are worn a bit.

Here pages 40-43 shows you how to check and shim the crank.

Remove the shim gasket and metal sim if there is 1 and measure the clearance between the cap and the block. If there is no clearance between the cap and block? you will either have to buy a metal shim. The metal shim is .010” and the paper shim/gaskets come in thicknesses of .004/.005” and .005/.007”.

If you measure it and you get .005 between the cap and block then you have to add .007 worth of shim gaskets. If there is zero clearance then you have to add a .010 metal shim and then measure it again. If you add a .010 metal shim and you still have zero clearance between the cap and block? I suggest Replacing the bearings.

Tecumseh part number 32031 is the .010 metal shim. Shim Gaskets are Part numbers 31970 (0.003-0.004) 31971 (0.004-0.005) and 31972 (0.005-0.007)

Bearings and Races are Tecumseh part number 31932 for the bearings and 31928 for the races. You will need 2 of each if it needs new bearings. They are Timken or NTN National bearings and races depending on the year of the engine so you should be able to pull the part numbers off of them and get a set fairly easy. They are clearly marked.
Thanks! I will tear down the engine sometime and check the crank roller bearings. The bearing looked pretty good, but can I just take the flywheel off and check/shim it without taring down the engine? Also is this something that I can just leave be and not have much damage to the engine or do I need to fix it before I work it. Only reason I ask is because of other Tecumseh owners say they have the same rattle with no other issues. Thanks again!
 

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Ya just pull the flywheel and check it. Make sure that you carefully remove the shim gasket. They usually come off in 1 piece but they do get brittle.

The last one that I rebuilt one that had a slight knock afterwards. I pulled the flywheel and just removed the shim gasket and that fixed it. Make sure that your O-Ring is still in 1 piece or it will leak oil if you remove the shim gasket.

If you let it rattle like that it will wear your rings out pretty fast and your bearings will get worse. That knocking is the bearings hammering on the races. The piston will cock a bit sideways on every stroke which is hard on the rings and the cylinder.

Do you remember if there was a metal shim when you pulled the crank to have it ground?
 

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Discussion Starter · #5 ·
Well this is interesting there is not metal shim or gasket shims on the plate at all. There is absolutely no clearance whats ever between the plate and the block. The bearings and race look pretty good. Is this the knocking problem? Also from what I understand the metal shims are used to reduce crank play and the paper gaskets are meant to fill the gap and stop leaks in between the plate and block. Am I thinking of this right? Thanks!
 

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The O ring seals the plate. The paper shim/gaskets just shim the plate out to set your end play if it is to tight.

No shim or shim gasket and there is no clearance between the plate and block? No clearance on the plate means it probibly needs new bearings and races especially if it is knocking. There should be some clearance between the plate and block without the shim gasket installed if the bearing is making contact with the race.

Let me try to explain this. The .010 metal shim is used if the end play is to tight. It pushes the plate and race out away from the bearing and the thinner paper shim/gaskets are used to set your end play. Example if you use a .010 metal shim and you get .002 clearance between your plate and block you will want to add .002 to get zero end play + .001-.007 to set the recommended end play. So .002 + .001-.007 in paper sim/gaskets to get .001-.007 end play.

You might get away with pulling the race out of the plate and shim the race out but the race will probibly break. They are pressed in and they don't like to come out. The .010 metal shim will work on either side of the race.


What gasket did you use on the cam cover? Is it an OEM Tecumseh gasket or aftermarket or a home made gasket? A thicker gasket will effect the crankshaft end play. I have gotten away with using a thin layer of permatex ultra grey instead of a gasket to tighten up the end play.

The aftermarket gaskets and gasket paper is much thicker than the OEM gasket. OEM gasket is only around .006 thick. Gasket thickness is critical. The thinnest gasket material that the auto parts place down the road sells is 1/32" which is .0340". That is way to thick lol.


I used a thin layer of permatex ultra grey on the HH100 on my 68 Custom 10XL instead of buying bearings. You will still have to check and set your end play on the cap afterwards but it works. Eventually the bearings and races will need to be replaced but it will run a long time before it starts knocking again.
 

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Discussion Starter · #7 · (Edited)
Ok that makes much more sense. I used a nos gasket from Ebay. gasket The gasket problem could be correct! The whole reason this rebuild charade started is because I took off the camshaft side cover to fix a leak from that plate. My plan was just to replace the gasket. The gasket that came off was EXTREMELY thin and I thought that was the problem. I replaced it with an aftermarket gasket which was also really thin, but not to the extreme. I put some gasket sealer on it as well and the leak persisted, but the knock was not there. So I took it off again and put another gasket on (slightly thicker than original) after I sanded down the cover on a flat piece of glass (fine grit) to make sure it was flat. That's where the problem started. When I fired it up it immediately started rattling. I figured it was a rod knock and reluctantly ordered a new rod after I had the crank measured. It was in spec so I ordered a aftermarket rod and rings for the piston. It immediately started rattling. So I took the engine off and tore it down. I used plasti gauge and the clearance was way to big. So I took the crank and .010 over rod to the machine shop and they clearanced it to 1 to 1.5 thousands. That worked! Although it is worth mentioning that this cover gasket was much thinker than the original gasket. I put it back together and it ran great with no rattling! For a while that is. I broke it in properly and changed the oil very frequently to make sure it cleaned out. (SAE30) It ran it for a good while, but then the rattle came back. This time much quieter. I discovered by closing the point gap it would make the noise go away completely, but it was really hard to start. So I put the points back to .020 and let it rattle. (not for to long) It is not very loud and it has not gotten worse. Thats where I am now. The engine is in the tractor and the flywheel side is taken apart so I can look at the bearing cover. Could my problem be the gasket that is much to thick? Thank you very much for your help! I would not have even thought as the gasket maybe being the gasket.
 

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The gasket and sealant is most likely your problem. Replace the cam cover gasket with an OEM one without using permatex and use a torque wrench on the bolts. Around 15-18 ft lbs should be good.

You can remove the cam cover without pulling the engine. Disconnect the governor arm and it will pull rite out. I did that on my 10xl. Make sure that you don't loose the little Hat looking thing on the governor gear. Put a glob of grease in it to hold it in place because it likes to fall off when you try to re-install the cam cover.

If you still have a slight knock just use Permatex Ultra Grey. Put it on and assemble it but do not add oil for about 24 hours. Let it fully cure. I put that stuff on a OHV mower valve cover and 3 years later I had to remove it to set the valve lash. I bent the valve cover trying to pry it off. Ended up prying and cutting it with a razor. It sticks really really good if you let it cure before adding oil.
 

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Discussion Starter · #10 ·
Well I did exactly that and I guess that was not my problem. The oem gasket was much less thick just what I needed. I put it back together with some fresh sae30 and it rattled louder than all the other times it had been put back together. Now it is worth saying that the top middle bolt (longest one) broke off and I had to take it completely out. I figured that since it was the top middle one it would not make much difference. (I will be purchasing one very soon) It must be the bearings that are causing the rattle. Also this is a little off topic, but I am using providence automotive oil from rural king. Have you ever had an engine not lubricate properly because the engine oil was not up to par? Thanks for all your help!
 
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