Murray engine troubles

[handirifle]

Go back and find out who had an engine and was willing to give it to you... Pay whatever it takes for him to ship it to you... Sheesh!

No way am I going to pay big bucks for an unknown engine. It may or may not be the same horse power, may not be in any better condition than mine was. Remember, this mower ran fine when I first brought it home. I have very little faith in used engines. I have seen too many lemons picked up that way and would rather try to fix mine or replace it with new.

The B&S repair guy says this is common with these engines, so any used engine might be just as ready as mine was to do the same thing.

Jim,
I will look again,to see if it is located somewhere else. I got this number off the cowling that covers the flywheel. So far it's the only one I have found.

Progress,
Last night, after studying the B&S web site and reading up on removing the valves on this engine, I made up a makeshift spring compression tool, and managed to get the exhaust valve out. So far I am very optimistic, since I discovered that about 75% of the lip the valve seat rests on, is still intact.

I took some pictures to give you an idea, and record what I chose to do.
I had already removed the valve, but placed it back in like it was when I pulled the head, so you could see what I saw.

First pic is what I saw when I pulled the head off at first.

Same shot, different angle. Notice how the valve seat is angled out, unevenly. It was sticking out on the left side, and resting down inside the plenum on the right.

Next, you can see the damage done when it came loose. In this pic, I have already dremmeled the area a little. There was some metal preventing the valve seat from going back into it's original place.

Next, is a pic of the seat removed and laying on the tire. As far as I can tell it looks perfect. The outer edge of the seat has zero marks on it, indicating no metal has apparently been removed from it, and it is not out of round.

Finally, after I cleaned up the recessed area, I tapped the seat back in place, and slipped the valve back in, to have a look see. It's still, suprisingly, a fairly snug fit. Not sure how much force was required when it was new, but I figure, when my friend Tig welds in the gap areas, I can leave a few extra .000" to make it a tighter fit still.

You can see on the lower left where the valve seat cut away material near the seat. I will get that filled back in too, and grind it smooth. Luckily, that will not have to be a machined surface.

My friend is supposed to come by tomorrow, hopefully, and if he does, I will post updates. I have to go to th B&S web site now and order their spring compressor and some new gaskets. So far all I need are head gaskets, and a gasket for the valve service area cover.

 

[handirifle]

Well, all attempts to obtain a Tig welder, by the friend, have fallen through, so I will look into other methods of repair, short of totally dismantling the engine to take it to a machine shop. That is my last resort, prior to completely replacing the engine.

 

[Molerj]

Not to be pessimistic, but I would be real suprised if you were able to repair this. Just my opinion but an educated one. If and that's a big if, it is able to be tig welded, then you need to have the seat cut & the valve lapped in to proper specs. BTW, I have never heard of anyone doing anything other than peening the old seat back in & as you have shown, there is too much damage for that to happen.

 

[handirifle]

Not to be pessimistic, but I would be real suprised if you were able to repair this. Just my opinion but an educated one. If and that's a big if, it is able to be tig welded, then you need to have the seat cut & the valve lapped in to proper specs. BTW, I have never heard of anyone doing anything other than peening the old seat back in & as you have shown, there is too much damage for that to happen.

Moler
I have no experience welding alum, but there are a couple possibilities here. First, luckily, the seat is steel, and is a seperate piece of metal, and still in perfect condition. What I need is the repair of the 40% of damaged shelf that it sits on.
I'm not making any bold claims here, just explaining the ONLY options I have left. I just spoke to B&S customer service, and the engine they recommend as a replacement is nearly $900, and that's before tax and shipping. Just a little steep, for a $500 mower.

Honestly, I'm gonna play with my Mig (since the Tig deal fell through) and if that is a zero possibility, then there's some aluminum repair putty or JB weld. I have NOTHING to lose.

Let's see, I can trash the engine now, or "fix" it and hope it works, or worst case, it trashes itself again. I only hope I can patch it and get some use out of it before it goes bye bye. With it costing me $150 each time to get my place mowed, just a few mowings will pay me back.

I can only hope here.

 

[Molerj]

Good Luck! And I agree, a Murray mower isn't worth putting much money into.

 

[handirifle]

I don't care what BRAND it was, if I buy one for $500 I'll not put another $900 into an engine. I'll save my pennies and buy a new Husqy.

By the way, B&S told me that although mine is a 20hp, it has a much larger displacement than current 20hp models and they recommend a 24+. That might be why the discrepancy in model numbers.

 

[handirifle]

Well, I used the gray aluminized epoxy putty, took the dremmel and scored the area to be treated. I then filled in the gap areas with the putty and drove the valve seat back in. I then cleaned up the excess and let it dry.

After a few days of sitting, I lapped the valve to the seat, and put it back together. Crossing my fingers, I started it up. IT RUNS!!!!! I actually mowed with ot for about 30 min, before having to get ready for an appointment.

Not sure how long but time will tell that one.

Now, I did notice some other issue, that valve may not have been the only problem. This one is not as serious. At lower RPM's like below half throttle, it surges, unless the choke is pulled partially out.

Now I have zero experience with governors on engines. i understand what they do, but never seen one work so not sure if this is a gov problem or a carb issue. My gut says carb. What, in either the carb or governor would cause a surging? And it's only below half throttle. Above that it SEEMS fine.

 

[2manyrocks]

Could be the carb passages are partly dirtied up or if it is old enough to still have adjustable needles, that the settings are a hair off.

I'm shocked it is running--next question is how long it will stay running...

It's odd to me that there appear to be several horizontal shaft engines coming out of China, but I haven't noticed any vertical shaft units of any size above the small push mower types.

 

[handirifle]

I'm shocked it is running--next question is how long it will stay running...

I hope it runs a long time, but we will see. I haven't started it again lately, since we've had almost 5" of rain since Friday, and I live in the bottom of a lot of hills = near marsh land. So I have some time before it can be used. If I take it out there now, it will be stuck for a couple weeks in the mud.

The only adjustment on this carb appears to be the idle. From what I have been reading in researching the surge issue, I will order a carb rebuild kit, and go from there. It's leaning towards the fuel pump, at least according to what I've read.

 

[robert thomas]

hi bobs the name. after reading all the post, why not look for another whole mower for parts?

 

[handirifle]

bob,
mornin,
Well, for one, mowers that have 20hp or more around here, are rare as hens teeth, Usually when they do show up they're about half the new cost, or $1200-1500, so even if this engine crapped out again, and I put a new engine on it, I am still out the same money, and I know what I already have.

Currently, I believe, all it needs is either a carb overhaul or a fuel pump (same place) so if I do that AND the valve repair holds for a season, it will help me save for a new mower. I have set my sights on the 26hp Husqy with the manufactured deck.

 

[MrFoPow]

bob,
mornin,
Well, for one, mowers that have 20hp or more around here, are rare as hens teeth, Usually when they do show up they're about half the new cost, or $1200-1500, so even if this engine crapped out again, and I put a new engine on it, I am still out the same money, and I know what I already have.

Currently, I believe, all it needs is either a carb overhaul or a fuel pump (same place) so if I do that AND the valve repair holds for a season, it will help me save for a new mower. I have set my sights on the 26hp Husqy with the manufactured deck.

What do you like in the Husq?

I'm genuinely interested because I looked at both today, and went with the Cub Garden Tractor.

 

[handirifle]

Well the 26hp one, is the one I was interested in. One item is the kawasaki engine. Smoother and quieter than others. A three rear front to back warranty. The rear tires are large enough to provide enough square footage of surface to keep it from sinking in in the marsh I call my property.

The mower deck is a manufactured deck, not a stamped one so it will stand up to all the 2" oak limbs I don't see in the 12" grass.

There's a local dealer, that has a good reputation for service.

That's about all I can come up with, but it's enough for me.

 

[handirifle]

She Runs!!!

Well, I got the carb kit in the mail Saturday, and installed just the fuel pump part of it today. I didn't rebuild the whole carb cause you have to understand my history with carbs. It's not a pretty one.

Soooo, I put the fuel pump back together, and after a few false starts to prime the carb back, it purred like a kitten. It idles very smooth and runs smooth at all throttle positions.

Now hopefully, a year from now, I can say the same thing, hoping the valve repair holds up. The guy that gave me the aluminum putty says he used it years ago on a 250cc dirt bike that ripped the threads out of the spark plug hole. He used this stuff to make new ones, and say he used it like that for a couple years, till he sold the bike.

Every day it runs, is more money in my pocket.

 

[handirifle]

Well, mowed for about 90 min today, and she still purrs like a kitten.:thumbsup:

Keepin my fingers crossed. That aluminum putty is amazing stuff.

 

[WilliamTO-35]

I'm glad you got your engine running. Products like JB Weld are epoxy with metal filings added, and an exhaust valve seat is a tough environment for epoxy. I hope it lasts. I had a valve seat fall out on a Techumseh engine, but I was able to do the peen and pound routine to reinstall it. I also had a valve stick open on another Techumseh engine. The valve stuck just after the guy next door borrowed the mower, and mowed with the throttle in the " choke" position . I think all of that fuel washed the oil off of the valve stem, and caused it to stick. My other neighbor gave me his riding mower with a 14 hp. Kohler engine that had thrown a connecting rod. He never checked the oil, so it was no surprise the rod went. I was able to find a brand new replacement short block on eBay for around $300, a lot less than the retail price of $800 or $900 . I had to find a different oil pan to fit the engine into my mower, but there again it was cheap on eBay. I was lucky on the output shaft specs. Kohler made several different shaft configurations, but my mower used the flywheel end to connect to the driveshaft, and the old flywheel works fine on the new short block. The mower is a heavy duty Deutz Allis hydro model, and well worth the effort to install another engine.

 

[handirifle]

I am amazed myself that this thing runs. I used it today for about 4 hrs straight, at or near full throttle. Still purrs on idle.

The dealer also told me of a repair for a stuck valve (which is what he first thought my problem was). He said to spray break free or similar onto the stem of the valve, and push on it. He claimed most of them will come loose again. Since that wasn't the problem, I never got to test that theory.

Glad you could peen yours, mine was beyond peening because it had hammered away too much material. I will look tomorrow, and post the name of the stuff I used. I ham a happy camper, so far.

 

[WilliamTO-35]

Besides overheating from blocked cooling fins, I think that running an engine at excessive rpm will lead to premature failure. While my Kohler is rated at 3600 rpm for 14 maximum horsepower, I mow at 2600 to 2700 engine rpm.
The engine has plenty of power at that speed, and if I get into very high grass or weeds, I slow down my forward speed or raise the mower deck to compensate. Mower deck drive belts also tend to burn up if overloaded .
I installed a small, digital tachometer/hour meter on my riding mower to keep track of rpm. I've long been amused at the difference between a Techumseh horsepower in a Sears mower and a Kohler horsepower. I had several Sears riding mowers with 12 hp. Techumseh engines and 38 inch mower decks, and they just barely had enough power to mow higher grass. My current mower has a 14 hp. Kohler and a 42 inch deck, and breezes through high grass without hesitation. There's a lot more than just 2 hp. difference between those engines ! I've also been happy with the smaller Briggs and Stratton engines I have on my 5500 watt generator, power washer, push mower, and snow blower. They usually start on the first pull, and run fine. The only problems I've had with recent vintage small B&S engines are the gas primer bulbs on some carburetors. Those bulbs seem to work sometimes, but not work other times. Fortunately, the generator and snowblower engines have a real choke, and not a primer bulb.

 

[handirifle]

I can imagine the engines were in all likely hood rated for the claimed HP, but what they do not tell is the torque. kinda like comparing gas engine hp to diesel hp. A 16hp diesel will do WAY more work than a 16hp gas engine, more than a 30hp gas engine, most likely. Your 14hp Kohler probably has a lot more torque.

As for me and running mine at high rpm, it was either that or the grass didnt get cut. This is a 20hp tractor, with 52" cutting deck, set up as high as it will go, BUT the grass is 12-18" tall, and a lot of it was wet. Most of the time I was never taking more than 1/2 the cutting width, and that's in 1st gear. I know this grass would tax most any riding mower. I'd much rather use a finish mower for my Massey Ferguson tractor, but my land is very soggy right now, and will be most of the summer, and I have gotten the tractor stuck twice already, and have no plans on taking it out there again, until it's drier.

I prefer to run it at about 1/2 to 3/4 throttle, but my grass was so tall, from the 20+ inches of rain we got on the last two months, and having the mower engine apart, I had no way to cut it. Besides, this was the first two dry days in a row we've had in almost two months.

If and when this dies, like I have said, I will replace it with a 26hp Husqvargna.

Cutting it from now on ought to be easier on me and the mower.

 

[handirifle]

Well, the saga continues.

As expected (not hoped) the previous patch did fail. big time. Back to square one with this project. I did get three mowings from it though, so not bad. These are 3hr mowings too.

I pulled it apart, again, and took another look. Yup it failed. So, this time I have taken a different approach. All this cause I'm broke/cheap and am trying the best I can to avoid spending three grand on a new mower.

This time, I used my handy little 7x12 lathe, and made a steel sleeve to hold the valve seat in. Not having access, or the funds, to pull the engine completely apart, and take it to a pro machine shop, I used (yes I really did) a 1 1/2" bi-metal hole saw to open the area around the previously partly destroyed section of block that contained the valve seat.

I am replacing the exhaust valve guide this time too, as it appears to be worn as well. Might have been part of the reason for the quick failure of the last patch, might not too.

So I machined a rod that fit the inside of the old valve guide, and would fit into the hole saw, and my 3/8 drill (did I mention this was a high dollar machine job?). I then drilled (using the term loosely) the valve seat area. This was scarry as all get out, cause now there was no turning back.

Once done, I measured the ID of the hole, and cut machined a section of
1 1/4" sched 80 steel tubing that I bought for this purpose. I machined the outside (1.5" roughly, don't remember exact size) to fit into the newly "machined" block. Then I machined the inside to allow me to press fit the old valve seat. Once done, I "pressed" the new setup into the block, and peened it into place. below are three pics of the work done. Sorry I didn't take pics as i went, my hands were too dirty to hold my phone.

I took a pic of the new sleeve with the valve seat, pressed in.

Then I took one with the exhaust valve partly inserted

Lastly is one with the valve completely seated. You can see the peening marks around it, to hopefully keep it all together. This thing fits tight in there, so I have high hopes.

My big concern, is this time, when I pulled the head off, there seemed to be a lot of oil in the cylinder, so I am hoping that the crap from the previous repair didn't take out an oil ring when it came off. We will see, I have about $50 into this repair this time. I am currently waiting on the new gaskets and valve guide. Supposedly tomorrow at noon, so in a day or so I will post the result of THIS patch job.

Anyone have any idea what the head bolts should be torqued to? I torqued them to about 50lbs last time, but was a guess.