165 (FB460V) overheating and losing power - MyTractorForum.com - The Friendliest Tractor Forum and Best Place for Tractor Information
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post #1 of 25 Old 04-10-2019, 12:26 PM Thread Starter
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Angry 165 (FB460V) overheating and losing power

I am still struggling with my 165 Hydro losing power when hot... last year it wasn't too bad, as long as I didn't try to mow grass best left to the 70 Diesel and bush hog! Still had to mow the 2 ac. lawn more often than usual, so it wouldn't overheat.

Now it's overheating (REAL hot under the hood and on the crankcase) and losing all power to the point where it won't even rev all the way up with the mowers engaged but not under load. It's getting so hot in the crankcase that the bottom of the plastic dipstick tube is distorted and causing an oil leak!

It does tend to backfire out the exhaust once on hot shutdown. No other blue or black from exhaust.
Difficult to restart when hot - no fire. no smoke. Think it's lean (gas boiled out of the carb bowl?)

When cold, it starts fine, and for 10 mins I can mow the grass as usual. In less than 20 mins. on a 75 degree day, it's losing power and slowing down again.

Things I have previously done/checked in the last several years:

Rebuilt the engine when I got it, because it was burning as much oil as gas. Honed, new rings, lapped valves, checked clearances. No smoke from exhaust.

Installed a tiny Facet electric fuel pump.

Replaced ignition trigger module in case that was the starting problem. No change.

Took carb apart and cleaned, all passages seem clear including main jet. Idles fine.

Gas cap vent is missing from previous owner, so definitely not obstructed!
....................................

Checked flow/pressure today when hot, way more than enough for a 12.5 hp engine.

On a hot day I think I can see boiling in the translucent fuel filter at the rear of the engine compartment, despite the 1-1.5 psi electric pump.

Carb body and bowl are WAY hot too. All factory heat shields, gaskets, and sheet metal in place.

I just removed sheet metal, no mouse or other debris, cylinder fins clean. Flywheel fins intact. Air blows vigorously out the air-cleaner hole in the side of the housing, when running without the air cleaner.

Is there ANYTHING you can think of... I've been working on cars/trucks/tractors most of my life and never met a head-banging-against-wall situation like this! Or is it just cheap gas with ethanol that boils too easily... Thanks for any help.

Last edited by DrCharles; 04-10-2019 at 01:57 PM.
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post #2 of 25 Old 04-10-2019, 01:13 PM
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Try running some premium gas in it. See what that does. Other thought is head gasket.

The 6 or so FB460V I’ve had are little powerhouses for 12.5 hp. and never had heat problems even in waist high grass.

Personally I run only straight gas.

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post #3 of 25 Old 04-10-2019, 02:01 PM Thread Starter
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Re: 165 (FB460V) overheating and losing power

I also put a new head gasket on when I rebuilt the engine, of course, but it wouldn't be too hard to replace I suppose.
Also tried alcohol-free premium one year, didn't help.

I did discover that a big chunk of the carb heat shield (the phenolic spacer about 1/4" thick between the carb and intake elbow) was missing. Hot air comes off the cylinder fins right next to that area, too. So I made a shield from shiny aluminum flashing to replace the missing piece. No improvement

Took a look at the blades and they are about as sharp as a stick of butter... going to sharpen or replace them. That always makes a significant improvement in performance. Maybe I'm just overworking the darn thing with dull blades!
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post #4 of 25 Old 04-10-2019, 02:29 PM
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Re: 165 (FB460V) overheating and losing power

How's it behave without the air filter on? Some weird ventilation condition that's leaning it out, maybe? Maybe dull blades (like you think), maybe your PTO clutch dragging or something? Not sure how you'd test for that tho...
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post #5 of 25 Old 04-10-2019, 02:58 PM Thread Starter
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Re: 165 (FB460V) overheating and losing power

Had another (new) set of blades hanging on a nail... changed them out. Only made a small difference, but now that it's above 80F, the engine started losing power after only ten minutes.

Anything dragging enough to overheat a 12.5 hp engine (that's 9.3 kw!) will get very hot, very quickly and I could just follow the smoke

I still suspect gas boiling causing lean mixtures and overheating, but don't know any other way to fix it other than the heat shield and an electric pump! Besides, the original setup with the feeble crankcase-vacuum pump didn't seem to be known for overheating problems.

I'm about to sell it for junk, or just set it on fire! It starts and runs the same without the air cleaner, but (when I'm feeling less frustrated) I will try a brief test of mowing without it.

Interesting you should mention the air cleaner though. Friend has a Great Dane zero-turn with a Kawasaki 17 hp twin, and it developed a weird misfire initially under load when revved up, that we finally decided HAD to be ignition coils going bad. Replaced them - no improvement! Gave up and took it to the equipment dealer.

They changed the (perfectly clean looking) air filter element... and it hasn't missed a beat since. Go figure.
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post #6 of 25 Old 04-11-2019, 07:00 AM
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Re: 165 (FB460V) overheating and losing power

Engines will run hot if the gas mixture gets to lean. Any chance there's a air leak in the intake tract? What color is the plug. The only problem I've had with those engines is that when they get a lot of hours on them the intake valve looses clearance and doesn't close. I guess you checked the valve clearances when you rebuilt it?
A friend at church gave me a 165 last year. He said it would run and quit after it got hot. Then it got to where it would not crank at all, I took the head off a month or so ago and found that the intake valve was not closing. When it was supposed to be closed I could turn it with my thumb. I took the valve out and ground it until I got the recommended clearance and it is running again, though I have not cut grass with it. Just guessing.
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post #7 of 25 Old 04-11-2019, 07:16 AM
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Re: 165 (FB460V) overheating and losing power

Here's the thread on the first one of the two I've found with the intake valve not closing.
https://www.mytractorforum.com/12-jo...mpression.html
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post #8 of 25 Old 04-12-2019, 03:43 PM Thread Starter
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Re: 165 (FB460V) overheating and losing power

I did check the clearances when I rebuilt it...

Unfortunately I just checked compression (cold), 65 psi. Low but within
serviceable range per the manual (55 psi or higher, 6.4:1 CR).

However... I put my leakdown tester on it and there is a LOT of air coming past the rings into the crankcase. With 90 psi on the left gauge, the right gauge is only at 31 psi

And the dipstick tube starts leaking oil at its base (plastic tube with o-ring seal to the aluminum base pan) when the air is applied to the cylinder. It never used to leak there, either, but is dripping oil when I run the engine now.

Maybe a very tiny amount of air is coming out the intake and exhaust. So the valves are definitely closed.
But this means either the piston is burned, or one of the top rings is broken. #[email protected]%.
Oil ring should be OK, there is no blue smoke in the exhaust.

I don't know if there's even any point in checking it hot, but I have to fire it up to move it anyway. Still wondering why it runs fine when cold, but makes no power at all within 10 mins of heating up... unless the hot combustion gases escaping into the crankcase are overheating it that way?
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post #9 of 25 Old 04-12-2019, 04:32 PM Thread Starter
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Re: 165 (FB460V) overheating and losing power

I warmed up the engine and mowed until I could feel it starting to slow down just a bit.
Repeated the compression check - 85 psi!
And the leakdown, although still massive into the crankcase, improved to 90/42.

Now I just don't know what to think. If the compression rings were shot (passing large amounts of blow-by), why am I getting good compression figures and not burning any oil?

If I am thinking about this right, a steel valve and tappet expands less than the aluminum block, so valve clearances should get tighter as the engine warms up? (The seat moves further away from the cam and toward the valve head).
Anyway there's no huge regurgitation through the intake... I wonder if the intake valve is sticking when the engine gets fully hot?

Or could the crankcase vent/oil separator be gummed up and not returning this (possibly normal?) amount of blow-by to the intake tract, so hot gas is trapped in the crankcase?

I'm stumped.
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post #10 of 25 Old 04-12-2019, 04:56 PM
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Re: 165 (FB460V) overheating and losing power

I think that in general those are good engines, I have 2 of them. The 165's are solid tractors but not running their worth almost nothing around here, I was given 2 last year. If I were you and wanted to keep the tractor I would watch Craigslist and Facebook for a 160 or 165 cheap and use the engine or shortblock out of it. Hopefully you have another mower and can walk away from that one when you get frustrated.
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post #11 of 25 Old 04-12-2019, 07:10 PM Thread Starter
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Re: 165 (FB460V) overheating and losing power

I'm already frustrated and it's my only mower. When I'm on vacation, I pay my ex or her son to do it... at least I got it mowed once!

Can anyone tell me, which direction the reed valve for the breather opens? It's hard to tell from the manual. I think it opens upwards, which is the way I had it installed. But that plate can go in the little box underneath the flywheel either way. (I pulled the flywheel to check the key, which isn't sheared).
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post #12 of 25 Old 04-12-2019, 07:22 PM Thread Starter
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Re: 165 (FB460V) overheating and losing power

I did some searching and it turns out that I did the rebuild four years ago to the day... it hasn't got all that many hours on it though, since we take a long summer vacation and I pay to have the yard mowed while out of town.

Perhaps it's time to pull the head and the tappet cover, and take a look at the bore and the valve clearances...
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post #13 of 25 Old 04-14-2019, 06:13 PM Thread Starter
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Re: 165 (FB460V) overheating and losing power

It's a cool breezy day... tank was nearly empty, so I put it back together, filled it with no-alcohol premium, oiled the foam pre-cleaner hoping maybe it was running lean without the restriction of oil, fired it up (has always needed several seconds of cranking when cold even with choke completely closed), started mowing lightly.

Not all that much power at first, but able to maintain RPM in light grass.
Just as ever, it started slowing down (checked to make sure the throttle was wide open).
After a few more minutes, I could either run the blades or move the tractor but not both. It couldn't even haul me up a modest hill with the blades disengaged. And it won't even rev to full RPM with the blades off, sitting still!

I shut it off, drained the bowl (gas wasn't particularly hot), let the electric pump run with the drain open for a few seconds then refilled the bowl (to make sure hot gas in the carb wasn't the issue). It started right up... but still no power at all.

Hydro unit is cool to the touch, brakes are not dragging, blades/spindles turn with little effort.

I have concluded that the engine internals must be defective somehow. Either it's binding up as the piston expands, or the rings are worn out (although I can't see how with 65 psi cold, 85 psi hot compression and no blue smoke!) The only Hail Mary left before pulling the engine is checking the intake valve clearance. (Again, it starts fine hot, just takes a bit of cranking when full cold). That means I get to take off all the tin again, and the carb, and the head.

I'm about to just look for a good used rebuilt FB460V-BS00 (JD), or maybe repower the @#$% thing with a different engine. I really don't feel like trying to rebuild it again since the by-the-factory-book didn't fix it!
Any ideas?
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post #14 of 25 Old 04-14-2019, 06:25 PM
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Re: 165 (FB460V) overheating and losing power

85 hot isn't that much compression IMO. I think you'll find the rings are shot. What did you hone the block with when you rebuilt it?

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post #15 of 25 Old 04-14-2019, 06:31 PM Thread Starter
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Re: 165 (FB460V) overheating and losing power

Well, it's only got 6.4:1 compression so I would not expect any more than that. The Kawasaki factory manual says the minimum acceptable is only 43 psi in one place and 55 psi in another. But there is lots of blowby on a leakdown check, as I mentioned...

I used a brand-new 240-grit dingle hone, ordered to match the bore size. Had a nice crosshatch pattern and hardly any taper to a dial bore gauge with .0005 resolution. It still doesn't burn oil (visibly). Doubt there's even 100 hr on it, and I did use straight 30 oil and change it per the manual. ???

This time I may take the block to a machine shop, if I can even find one that knows their way around an FB460V.
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