Engine Issues??

[Jdv007 3]

A short while ago I asked for some help with problems I’m having with my 1972 Wheel Horse Raider 14 engine.  I've had an abrupt loss of engine performance a couple of weeks ago.  I’ve done quite a few things to try and fix the problem, but nothing has worked.   I'm still dealing with the original issues described below:

1.    When I start mowing the engine runs good, but after about 15-20 minutes the engine starts missing, loses power and rpm, and is noticeably hot. Adjusting the high and low Kohler carburetor needles does nothing to correct the problem
2.    Lots of back firing and popping
3.    Oil sprays out of dip stick tube when the stick is removed while engine is running
4.    Always starts easily when cold
5.    Small oil leak on what appears to be on the right front side of engine

Most Recent Fixes:
1.    Checked and found good airflow under the engine shroud
2.    Changed the fuel filter
3.    Changed oil
4.    Installed new coil
5.    Installed new plug
6.    Installed new wire from coil to spark plug
7.    Installed new carburetor
8.    I’m using fresh gas, and have run the engine with gas tank cap off with no change in performance
9.    Gas tank outlet and all fuel lines are clear and open.
10.    I replaced the fuel lines, shutoff and fuel pump about 3½ years ago
11.    Installed new points and condenser about 1½ years ago

Are these symptoms possibly from the points needing adjustment?  Or do I have I have some engine issues.  Are any of the symptoms I’ve described a sign of valve, pistons/rings, or other internal engine problems?  I’ve had this 48 year old machine since I purchased it in 1987.  I love the old tractor, but I’m getting frustrated with this current issue.  Any ideas about how to proceed would be very greatly appreciated.
 

[gwest_ca-(File Mod) 11,482]

Easy to do so try another condenser.

It is connected to the (-) side of the coil? and the metal condenser body requires a ground.

 

Garry

[Ed Kennell 41,974]

Try it without the muffler.

[ebinmaine 72,672]

5 hours ago, gwest_ca said:

Easy to do so try another condenser.

It is connected to the (-) side of the coil? and the metal condenser body requires a ground.

 

Garry

Condenser was my first thought as well.

 

Check and adjust points.

 

 

[SylvanLakeWH 28,400]

6 hours ago, Ed Kennell said:

Try it without the muffler.

 

Curious... what issue would this target?

[The Tuul Crib 7,339]

I agree with Gary . You could have 

a bad condenser or not grounded

good enough.

[953 nut 59,995]

1 hour ago, SylvanLakeWH said:

8 hours ago, Ed Kennell said:

Try it without the muffler.

Curious... what issue would this target?

       An engine is an air pump. Anything that restricts the intake or exhaust will harm performance. I always like to do the free (no cost) symptom checks first.

If the muffler has a partial blockage if will cause the engine to labor and won't allow removal of exhaust heat.

[Ed Kennell 41,974]

1 hour ago, SylvanLakeWH said:

 

Curious... what issue would this target?

Jim, A neighbors church had a 314 that had some of the same issues, overheating, pressure in the crankcase, loss of power.

After chasing the usual causes, points, condenser, plug, fuel supply, breather cleaning , without success,  I found the muffler was clogged.  

Problem solved.

[Ed Kennell 41,974]

12 hours ago, Jdv007 said:

 

2.    Lots of back firing and popping
 

11.    Installed new points and condenser about 1½ years ago

Are these symptoms possibly from the points needing adjusted.
 

Yes, back firing and popping could be  a timing issue.    I have found the points need to be gapped at 0.018" to get the timing correct instead of the 0.020" as stated in the manual.    To get the timing correct on one engine, the points gap needed to be set at 0.015".

 

All the other symptoms indicate a clogged muffler.

Edited June 11, 2020 by Ed Kennell

[Lee1977 7,208]

3 minutes ago, Ed Kennell said:

Yes, back firing and popping indicates a timing issue.    I have found the points need to be gapped at 0.018" to get the timing correct instead of the 0.020" as stated in the manual.

 

All the other symptoms indicate a clogged muffler.

 Or in need of a valve adjustment. If this engine hasn't been apart in almost 50 years the carbin build up could make it run hot. It's time to take a look inside and see what he's got.

[Tuneup 1,452]

... and jd, let it love its fuel. Adjust it when warm a little on the richer side. It is air cooled and a lean adjustment with constant load will lead to overheating. Yes, pull the muffler and then adjust it a little rich but not so much that she coughs on part throttle. You'll probably be just fine. Let us know!!

[oilwell1415 563]

I agree with checking the muffler first because that's free.  Another free thing to check is fuel flow since you say it is noticeably hot when this happens.  I know you listed pretty much everything in the fuel system as replaced, but actually put a fuel pressure gauge on the outlet side of the pump and monitor fuel pressure with the engine running.  If it's getting lean it will run hot and if it runs hot it could cause a valve to start sticking which would cause the problems you describe.  A valve could actually be sticking anyway due to carbon build up, but I'd rule out everything else before I opened the motor to check that.

[ranger 1,798]

I have a 312-8, either 87 or 89, with around 850 hrs on it, this has the Magnum engine. I copied the muffler in stainless after the original rusted out. It is very quiet when running but after a while it starts to lose power, backfire and will stop if I don’t close the throttle quickly. It will start up again immediately. I have tried a new carb, plug, pump, etc, no change. Turning the muffler 90 degrees to allow better airflow appears to help.Running at 3/4 throttle it runs for longer before playing up.

I had read somewhere that Kohler had problems with the Magnum engines whereby the exhaust valves would occasionally seize due to too tight a tolerance in the guide, I believe a service bulletin was sent out to dealers advising reaming out to a looser fit.

I haven’t got around to pulling the head off to investigate yet, mine also runs hot when this occurs.