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Hi Guys

After some advice. I have just stripped down my cylinder heads after a bent pushrod and corroded exhaust valve was discovered. I took ownership of the mower with this damage so am trying to get it back up and running as cheap as possible so I can check out the rest of the components.
Both cylinder head gaskets were leaking and the barrels were caked with dried oil / carbon. The side with the bent pushrod on the exhaust the valve seat had dropped out slightly. The valve is corroded and will need replacing.

Unfortunately the valve seat has a tiny hairline crack down the side nearest were the corroded edge of the valve was. I have tapped the valve seat back and plan to peen the edge to stop it dropping back out. In theory I know a new head is in order but until I can access the running engine I don't want to spend lots of money on something that may work out cheaper getting a new engine completely.

I have cleaned up both heads and the valve seats and existing three valves seem good condition so I plan to buy a new exhaust valve, lifter, four pushrods, four springs, stem seals & head gaskets to get her back up and running. Also I will lap in the valves prior.

My only concern is the cracked valve seat but I plan on stripping the mower over winter (Australian) so will fit new cylinder heads etc then.

Attached is the two cylinder heads one showing a crack.




Can the exhaust valve seat be reseated as I don't see any part numbers for valve seats anywhere?

Thanks for any input.

I didn't find parts numbers for the seats either, but did find that the part number for the head has superceded twice.

Since you do your own work the repair attempt to the loose seat may be worthwhile. I do remember guidelines from Corvair repair where peening was used. But I think that method will not hold up. Try tradeoff of weld fill and remachine vs new head. However , again, I do believe the degradation of the aluminum alloy (softening) during weld could ruin the whole effort. Berts...?

The Command Pro engine do not have replaceable valve seat inserts. You are down to two choices, find a used head or purchase new. Sorry for the bad news.

And it will leak like a sieve through the crack which will pressureise the crankcase cause more blow by and all your good work will be a waste of time.
Buy a new head.
Now that Prime Line has exited Australia I get all my Kohler parts from Jacks Small Engines in the USA.
Including postage ( use USPS ) they are 1/2 to 1/4 of the local price due to Kohler's wholesale pricing policy and 100% retail mark ups.
Eg your flywheel $ 770 in OZ / $ 125 in US , your stator $ 475 in OZ / $ 122 in USA.

Those Kohlers are very robust so check the rods for play and the cam shafts for wear in the bushes, buy the new bits & button it up.

Yeah I agree I probably should buy a new head. My main concern is if I get it all back together it may need new oversize pistons and reboring and I read somewhere that some of these engines can't be rebore but then again they sell the oversize pistons & rings for that model so go figure. Maybe someone can enlighten me.

If i was going down the path of a new head, I really should be using new valves, etc etc but then the price was creeping up again.

Bertsmobile don't I know about the price difference! That is why I am buying from US, we get raped here on prices. A new cylinder head locally is A$470, A$180 from US. Yes I am pricing all my stuff from Jacks Small engines although OPEngines also ship to Australia as do Shankslawn, all three have similar prices.

Some of the Kohler 25 hp engines used a nicosil plated cylinder which cannot be oversized. If the oversized parts are available for your spec number then you are probably OK.

I managed to get a secondhand head complete with valves in good condition. Same part number as well however how now discovered it came of a vertical shaft engine so the oil drain back is not drilled from the rocker side however I assume I can just drill it through.
Anyone done this looks pretty straightforward and can't see any other issues.

Guy I bought it off had a yard full of bits just lying around but was cheap.

Get out the Black & Decker and make a hole