# MTD 1998 5/24 Power Loss - Solved



## dlk4602

My 1998 24" MTD 5 HP Tecumseh was down on power and would only run with partial choke. After checking the carb and finding no issues, I was at a loss of what was wrong. After looking at the re-powering threads by Bain and GustoGuy, I was seriously considering going down that path.

After a little more research, I decided to check the valve clearances. It turns out that the exhaust valve stem stretched enough to prevent the valve from closing. Apparently this is a common problem with these flat head engines.

After adjusting the valve clearance it is now running like new.

If your having issues with your flat head engine and have gone through carb, it might be worth checking your valve clearances.

Dave.


----------



## HCBPH

Good info, glad to hear you got it fixed.


----------



## Edge

Definitely good info. I read about this also. Did you notice any popping out the exhaust,low compression or other symptoms? Did you have to lap the seat due to burning or were you able to just set the clearance? I just picked up a 2005 Yardmachines/MTD 5.5 HP/24, I am in the process of checking it out. So far-so good, but I have not blown snow to really test it out with a load yet .


----------



## dlk4602

The main symptoms were loss of power, hard to start and only ran with the choke 1 click on. I did lap the valves although they really didn't look that bad. From what I have read, you really cannot get a good compression test because of the compression relief on these engines.

I also added a homemade impeller kit using 3-ply baler belt. This has made a significant improvement in performance. You may want to consider doing this to yours.


----------



## Pythons37

dlk4602 said:


> My 1998 24" MTD 5 HP Tecumseh was down on power and would only run with partial choke. After checking the carb and finding no issues, I was at a loss of what was wrong. After looking at the re-powering threads by Bain and GustoGuy, I was seriously considering going down that path.
> 
> After a little more research, I decided to check the valve clearances. It turns out that the exhaust valve stem stretched enough to prevent the valve from closing. Apparently this is a common problem with these flat head engines.
> 
> After adjusting the valve clearance it is now running like new.
> 
> If your having issues with your flat head engine and have gone through carb, it might be worth checking your valve clearances.
> 
> Dave.


Great tip. Thanks.


----------



## Edge

dlk4602 said:


> ..... From what I have read, you really cannot get a good compression test because of the compression relief on these engines.
> ..............



I was thinking a little more about the compression test. On a good engine there should be some amount of compression even with the compression release. A quick approximate test I found is there should be some resistance when you pull the recoil on the Tec. If not, you have low compression. But it is not very precise. 

If you get a chance maybe you could do a compression test and we might have a known compression on a good 5 hp Tec engine for comparison. I am going to test my 5.5 hp Tec. It has a revised compression release compared to the 5 hp, so the number should be different.


----------



## Shryp

I was under the impression that these engines will register around 60 PSI on a compression test with the release device on them. I haven't checked any myself, but that was the number I saw on some videos.


----------



## Edge

Well, I got around to doing a compression test today - 75 psi dry and 87 psi wet at about 85 deg F. I didn't have a chance to warm it up to temp, so that probably accounts for the 16% diff between dry and wet. No rocking on the needle, so valves seem OK. Still, it looks pretty decent. I'll see if I can get a comp test at operating temp.


----------



## nelsontj

May I ask what you used for valve clearance? My owner's manual on my Sears Craftman 5hp (Tecumseh HSSK50) flat head lists .010 in for both intake and exhaust. I have seen other listings for .008 intake and .010 exhaust. for that engine.


----------

