No power under load

The trouble, I have no power under load. Using a brush hog or finish mower, if the grass gets just a little tall (hog) or thick (finish mower), the old 8N will bog down or just flat die, even in 1st gear at near full throttle.

I have also noticed the tractor seems to be getting hot. There is no thermostat installed and the fluid level is just over the core fins in the radiator. After running under a slight load for a while, even on a cool day (60s), when I shut down I can hear the coolant bubbling/boiling in the engine.... 50/50 mix of antifreeze/water. I have run with the cap off and can see the cooIant ciculating quit well.

I am also getting a "pinging" or "knocking" under load.

On the other hand, the tractor always starts easily and idles fine... it does seem to take a while to warm up... several minutes before I can take off without the engine sputtering or dying (no thermostat?). Once warm... 3 - 4 minutes, no trouble.

Here is what I have cheked thus far.....

Fuel supply - good fuel flow and I have made sure the screens in the carb elbow are clean - not obstructed.

Compression - ran for a few minutes and checked with all cylinders dry 120-120-90-90. Maybe a weepy head gasket? I have found no eveidence of water in the oil, or oil in the cooling system.

I have done Dells governer check,,,grabbed the carb link and accelerated and the governer pulled back pretty hard.

I have not changed points yet (front mount distrib.). Good next step?

Anyway, suggestions appreciated. I have been using the tractor this winter to pull a small trailer for hauling wood around, and not really putting a load on. Runs just great using for that. Went to hog some dead grass before it started growing again and the power loss seems to be much worse than last fall.

Thanks in advance.

Odie1

You write..... "I have also noticed the tractor seems to be getting hot. There is no thermostat installed and the fluid level is just over the core fins in the radiator. After running under a slight load for a while, even on a cool day (60s), when I shut down I can hear the coolant bubbling/boiling in the engine"..... ..This very common for a backassward installed thermostat. And how do you KNOW??? you don't have a thermostat installed in your upper radiator hose??? Prove it!!! Stick a long screwdriver thru the hoze. bettcha can't!!!

You write..... ."I am also getting a "pinging" or "knocking" under load"..... .well no wonder, OVER-HEATED engines ping/knock..... .just as too advanced spark timing causes knocking (that ain'chur problem 'cuz too advanced timing causes engine hard to start, not your complaint)

...or... TOO LOW-OCTANE gasoline will cause knockin' in HIGH-COMPRESSION engine (that ain'chur problem 'cuz yer 6:1 low compression flathead enging was designed for 70-octane unleaded gasoline and todays modern no-lead gasoline is at least 86-octane)

You write..... ..."On the other hand, the tractor always starts easily and idles fine"..... ..rules out weak sparkies and bad carb idle adjust.

You write..... ."it does seem to take a while to warm up... several minutes before I can take off without the engine sputtering or dying (no thermostat?)"..... ..while this complaint could be cold-engine related, I DOUBT it!!! (not with your over-heating complaint) ...but... it is VERY RELATED to MISS-WIRED sparkies. Like I said (and others) check'em-out; 1,2,4,3 CCW.

And while could be a slightly lean down-pointing mainjet (enrich 1/8-turn CCW at a time) I doubt it.

and Odie, thanks for an EXCELLENT POST, keeps me from having to mindread..... ..Dell, the failed mindreader (just ask my ex-wife)

Dell, thanks for the compliment... I have a pretty good idea there is no thermostat....since I put new upper and lower radiator hoses on last fall...

Today I re-checked and didn't think I was getting good fuel flow, so I recleaned all the screens - the carb elbow and took the sedement bowl assembly out of the tank and cleaned it also. (funny story - found a screw driver in my gas tank!). Went and mowed again and power seemed a little better - but I really didn't get into anything heavy to really test it out.

While mowing, I did get hot again. This time got a little "spew" out of the cap.

I needed to change oil, so I checked very carefully for any signs of water in the oil... none.

I did discover - BEFORE mowing - that I was down about a quart and a half in the radiator.... took that much to cover the core back up. The radiator is clean front and back.

So what could be causing it to heat up like it is?

Thanks again
Odie1

To answer a couple of questions, I have had the tractor for 5 years and the trouble seems to have been slowly getting worse. I typically use it to finish mow, and I try not to get behind, so there will not be to much load on things.

As for the raiator cap, I have 2, a 4 lbs (which is the stock rated one... I think) and a 10 lbs. I cannot detect either leaking, and I will get the "boiling" effect with either one.

I will check the sparkie color this eve/tomorrow when time. I am 99.999% sure (never 100% posistive...will check again) the plug wires are on in the correct order.

I had another of these tractors years ago and remember its about a 30 minute job to change points.

Not sure I have ever checked the timing advance? Can someone refresh my memorey on how thats done?

I post an update when I get more info.

Thanks again
Odie1

Incidently, your #3 & #4 cylinder's compression pressures are low and identical so you might have a head gasket leak between them. Are you seeing any bubbles in the coolant?
hope this helps you.

frank

• Hobby farm

I would start with a tune-up; new plugs, points, condenser, & wires.

Plugs: Autolite 437 set at .025"
Points: Blue Streak set at .015"
Wires: Copper wires, not carbon core

Distributor comes off with 2 bolts and you put the points in it on the bench.

Good luck,
Danny