[Dave4514]

All this talk about the oil pump drive gear failing got me to add an oil pressure "Idiot Light" to my 4514. There are only a few things I could come up with that would cause the plastic gear to fail. One is wear as LarryCCF mentions and another might be if the wrong weight engine oil is used in cold weather. The owner's manual shows a chart of oil weight vs. temperature and specifies that 10W30 or 10W40 should be used for temperatures down to 0*F. If a heavier weight oil is used or a straight 30 weight, it will put more stress on the gear. Another possibility is a clogged oil filter. I don't think Honda uses a filter bypass valve in the block. If the filter clogs the gear will be heavily loaded. To ease my mind the light I added may give me a little time to shut down the engine.

Honda specifies the oil pressure at 2kg/cm or 28.4 psi for this engine. I found a switch made by Autometer that will turn a light on with a pressure lower than 18 psi.

Here is a photo of the main oil gallery on the spark plug side of the engine. The fitting for a sender is blocked off with a plug. Unfortunately Honda put a motor mount just below this plug.

I had to grind away some of the mount and use a 45* fitting to allow room. Here is a photo of the sender installed.

The idiot lamp is made by Dorman and uses LEDs.

Here is how it looks on the dash. The "Low oil pressure" label was made using my printer and is held under some clear packaging tape.

Wiring for the idiot light was simple. I used a switched +12 volts from the ignition switch to go the lamp + terminal and from the lamp - terminal to the pressure switch. This pressure switch will connect to ground with an oil pressure less than 18 psi.

 

[larryccf]

nice idea & execution :thThumbsU

 

[mchucker]

good idea on the oil pressure light, I installed a oil pressure gauge on my 3813 as well as a coolant temp gauge, both of those gauges mounted easily low under the steering wheel. I like the idea of a light, though, more of an attention getter than a low needle .

 

[rogerb]

I have a 25 year old engine in my tractor with the orig oil pump gear. I have always used premium synthetic oil in it. I would expect it to give me a few more years of service hopefully. My thinking is that a lot of owners don't think that there is a diff in oils and use dino oils because that's what they have always used. Believe it or not I run my synthetic a couple years before it's changed out. Its always fairly clean looking too.
Anyways, I like the idea with the lite and well executed too. It would be nice if you could figure a way to run the ignition where the engine would stop at low oil pressure. Maybe 2 pressure switches??

 

[larryccf]

actually roger, you and i are on the same page as to oils - i've always used synthetics (Castrol) 20-50W in my 3813, and changed every fall - and you can see the difference in my thread to the wear on the teeth. Don't know what your seasons are like there, but here in Richmond, we start cutting the grass, 1st time in March, thru mid November, maybe a little later depending on how warm it stays. And I'm cutting 2.5 acres, so about 3 hours of run time per cutting.

i thought about it, and one measurement i didn't think to take is the diameter of the gear, to see how much the height of the teeth has come down, if any

if it's still in the trash i'll dig it out and mike it

my 3813 was purch'd Nov 1989 when i bought the house i'm in now, and was used every year since then, with the exception of 6-7 years when it was parked in the shed

the hesitation to change the gear, in my mind, was knowing while i had the PTO off, i'd probably be smart to change at least the bearings in it and whatever else that looked like it needed it. The burning smell forced me to pull it off and while off i simply went in deeper.

Now, while i'm waiting for an O ring to come in (that i didn't think to order), i'm wondering if i shouldn't change out the governor gear - it's also nylon, and if worn like the oil gear, would or could be the source of the surging i'm seeing at idle speeds.


PS - there was an uproar in some of the car forums that Castrol Syntethic isn't 100% synthetic oil - ie it's a blend of petroleum & synthetic. Which might explain something - when i change my tractor's oil in the fall, it has gotten dark - considerably so, not black but it definitely dark as strong coffee. I run Volymer's 100% synthetic in my Truck, and it doesn't change color, last time for 1.5 years with considerable mileage on it. ****, it even still felt slippery between my fingers when i changed it. But cost difference between it and castrol is pretty strong - approx $3.50 castrol vs $7.00 for volymers

and just measured the new & old oil gears - not much of a difference. Old gear ranged from 80.03 - 80.19mm, depending on where i measured it, and the new one 80.18-80.39mm. So say .20mm rough difference (.20mm = .008" approx), that could be within the mfgring tolerance, or possibly slight shrinkage by the polymer from age. I don't know the composition of this gear, but some polymers shrink or contract from age. Looking at the tips with a 12X loupe, i didn't see what i'd consider wear indications or marks. In the scheme of things, i don't think .008" is anything by itself to be concerned with, fwiw

 

[Dave4514]

mchucker, I thought that someone here on the Honda forum had installed a gauge but could not find the thread. I was unsure if you had to modify the engine mount as I did.

rogerb, your idea of killing the engine if the oil pressure falls is a good one and got me thinking of using the fuel stop solenoid on the carburetor to do that. The problem to overcome is how to allow the fuel to flow with no pressure when starting the engine.

Since I don't know how long it takes for the oil pressure to turn the pressure switch off, I will have to experiment with the values of R and C. I guess the longest time would be after a new oil filter is installed.

I have also always used synthetic oil, but maybe I'm over thinking this whole problem. :banghead3

 

[larryccf]

along the same lines of letting the oil pressure switch kill the engine, i had thought just using one of the honda pressure switches that do exactly that on all the generators - with no idiot light

the issue is looking at the engine svc manuals to see what their oil pressure limits are running, so you'll know which engine's switch to use

i've got a honda 20 hp twin (GX610) on a generator that i suspect is running the same oil pressure but need to look at the svc manual

believe all they're doing is running a lead to the magneto kill lead

 

[rogerb]

I have heard that Mobil 1 wasn't full synthetic but I have never heard that about Syntec. I wonder where one finds the truth? Actually, I run Amsoil in my bike and did in my vehicles and Honda mowers. It is considerably more expensive but as the old folk say "you get what you pay for". Larry, I do notice a darkening of Castrol but never connected it to dino-oil. Heck even if Amsoil(whick I consider the overall best) is more expensive, you aren't going to break the bank at the extended change intervals. And yes I used to be a dealer but not now.
Larry, I am interested in that plastic gear wear though.
On the oil light, it looks like it would take some experimenting to find the values. I would think that a float bowl full of fuel and no oil pressure would not be good though. The engine would have to run the fuel out of the bowl.

 

[larryccf]

the info i got on castrol was from a car forum i used to be on - a few of the members were petro-chem engineers and actually had folks or detailed the program for sending in oil filter samples so folks could tell what they're engine was giving up in the way of metals, dependent on the oil they were using. And the forum also said Mobil 1 wasn't 100% synthetic

and they also ran a regimen of tests on the different oils out there.

Surprisingly, Amsoil and Royal Purple were up in the top 4 or 5 in the tests (tests included a number of categories i'm not intelligent enough to even understand but i accepted those guys credentials).

Volymer's synthetic, out of germany, was actually one of the few oils Porsche and BMW recommended in germany

used to be available at trak auto for about $7 a quart, but they stopped carrying it. Found NAPA carries it but you have to special order it (5 liter jug for $35) which a few cents less

it just surprised me how clean it stayed and kept it's slippery feel whenever i'd test it between my fingers. when i changed my oil last time, it was actually out of an over abundance of concern, the oil really didn't look like it needed changing.

what i didn't realize about synthetic oils, they're much more tolerant of heat/cooling cycles than petro or dino oil, and since 95% of my driving is exactly that, ie stop and go driving around town, i figured i'd try it.

 

[larryccf]

found my svc manual for the GX610/GX620 V-twin honda engines - and the oil pressure on those is 28.4 psi, same as our engine. I suspect it's probably the same for all of the honda engines in this size. It'd be easy enough to confirm by checking the part number for the oil pressure switch on a few different engine - if it's the same, then they're all running the same pressure

i looked at both my gen and the 3813 engine, and without removing the plug in the 3813 or the pressure switch in the GX620, they look to be the same threading

as for the delay setting, i'd think you'd be able to test one of the honda pressure switches to see how long before they "trip".

and in case it helps Dave, i've also posted the 3 schematics for the GX620 (one general schematic and two specific to the oil pressure switch and it's link into the ignition switch) at http://s816.photobucket.com/albums/zz81/vze86qtl/oil pressure switch schematics/

 

[Dave4514]

Thanks Larry, I looked at those schematics but there is a lot missing as far as the real circuit. Honda shows a wire with an arrow pointing to a small rectangle which is Honda's way of hiding the real circuit elements present. But on my GX360K1 wiring diagram it shows the same pressure switch connected to a module called an "Alert Unit" and it looks like this unit uses a relay to allow the engine to start by blocking the zero pressure signal as the engine is cranking. After the engine is running the pressure switch will kill the ignition if the pressure is low.

I have the feeling that the same kind of circuit is used on your generator to ignore low pressure when starting.

 

[larryccf]

another approach might be to contact honda tech svc (number is in all the owners' manuals) - they've always been real helpful in the past

 

[larryccf]

one small factoid that might serve some to know, and is in line with roberb and Dave4514 using pure synthetic oil in his honda, we had a retired research lab chief from Dow Chemical here on a consultancy sometime back, and i remember him indicating that synthetic oils offered the best lubrication in plastic to metal interfaces, ie like the nylon oil pump gear & the cam drive gear.

Considering we've got two nylon gears in this engine, the oil gear and the governor, maybe it'd be better to run a pure synthetic motor oil. Plus the fact is, petroleum derived compounds are corrosive to most polymers - while i'm sure honda would have spec'd a polymer that had a tolerance, corrosive is still corrosive (and i'm using that word the the retired lab chief did). They degrade most if not all polymers over time, whether causing embrittlement, whatever

 

[Dave4514]

Sorry to bring back this old thread but I think there is a way to kill the engine when the oil pressure drops. I was thinking that when the engine is being started the solenoid on the starter motor gets a 12 volt signal and that could be used to throw a relay to ignore the oil pressure.

So here is my logic.
1) If the engine is cranking with no oil pressure the relay gets powered from the starter solenoid and opens the contacts to the "Kill" wire. If the "Kill" wire is grounded the engine will not start.
2) After the engine starts and there is oil pressure, the oil pressure switch opens and the engine runs normally. The relay is not powered and the normally closed relay contacts connect the "Kill" wire to the pressure switch.
3) If the oil pressure is lost, the pressure switch closes, lighting the idiot lamp and grounding the "Kill" wire. This will stop the engine in the same way as turning the key off.

This is the wiring diagram with the wires in blue added to the Honda harness. Most of it is already there. I just need to add a relay to my idiot light. The connection to the starter is right next to oil pressure switch.

I will be using parts from Radio Shack for this circuit.
The relay is part # 275-218
The relay socket is part # 275-220
A small project box is part # 270-1801
So for less than $20 my idiot light will now also stop the engine, a great deal!

 

[larryccf]

actually, i like it - as i understand the principle it's simple, don't see how it can fail

question for the electronically illiterate like myself: you've got "relay" written in twice, once on the lead by the idiot light and once on the lead (i assume the negative lead) from the solenoid

and that one's identified by a spring like icon - any help for idiots like myself on exactly what you're doing there

 

[Mike.ASC]

the info i got on castrol was from a car forum i used to be on - a few of the members were petro-chem engineers and actually had folks or detailed the program for sending in oil filter samples so folks could tell what they're engine was giving up in the way of metals, dependent on the oil they were using. And the forum also said Mobil 1 wasn't 100% synthetic

and they also ran a regimen of tests on the different oils out there.

Surprisingly, Amsoil and Royal Purple were up in the top 4 or 5 in the tests (tests included a number of categories i'm not intelligent enough to even understand but i accepted those guys credentials).

Volymer's synthetic, out of germany, was actually one of the few oils Porsche and BMW recommended in germany

used to be available at trak auto for about $7 a quart, but they stopped carrying it. Found NAPA carries it but you have to special order it (5 liter jug for $35) which a few cents less

it just surprised me how clean it stayed and kept it's slippery feel whenever i'd test it between my fingers. when i changed my oil last time, it was actually out of an over abundance of concern, the oil really didn't look like it needed changing.

what i didn't realize about synthetic oils, they're much more tolerant of heat/cooling cycles than petro or dino oil, and since 95% of my driving is exactly that, ie stop and go driving around town, i figured i'd try it.

I don't mean to butt in but I find this very interesting . I just looked at a bottle of Mobil1 I have sitting on my shelf and it clearly says "fully synthetic" . Does the wording "100% synthetic" and "fully synthetic" mean different things ? I would think that if there were any proof that Mobil1 was not 100% synthetic they would be inviting a massive lawsuit . If in fact Mobil1is NOT 100% synthetic then I definitely feel decieved....

Mike

 

[Dave4514]

question for the electronically illiterate like myself: you've got "relay" written in twice, once on the lead by the idiot light and once on the lead (i assume the negative lead) from the solenoid

and that one's identified by a spring like icon - any help for idiots like myself on exactly what you're doing there

I could have drawn a better looking schematic, but the relay written twice was my way of showing the relay coil and relay contacts. They are both parts of the same relay. The spring-like thing is the relay coil.

Tomorrow they are forecasting rain so I'll be in my garage trying out this circuit. If it works as expected (or not) I'll report back.

 

[larryccf]

I don't mean to butt in but I find this very interesting . I just looked at a bottle of Mobil1 I have sitting on my shelf and it clearly says "fully synthetic" . Does the wording "100% synthetic" and "fully synthetic" mean different things ? I would think that if there were any proof that Mobil1 was not 100% synthetic they would be inviting a massive lawsuit . If in fact Mobil1is NOT 100% synthetic then I definitely feel decieved....

Mike

it's fairly complicated in how they did it - but first the industry association agreed to a change in the meaning of "synthetic"

2nd, i'm not a petroleum engineer but from what i gathered, mobil simply changed something in the refining process of petroleum based oil (don't ask me to explain cause it was fairly technical, but something about "fracturing" or "hydrocracking" a component in the oil that they use to claim it's synthetic. Others seem to like to refer to it as a "virtual synthetic oil".

here's some google hits, and i'm sure there are a ton more

http://www.trustmymechanic.com/motoroil.html

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1496124

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2248265

here's one from an exxon/mobil 1 engineer
http://caradvice.askpatty.com/ask_p...res-the-truth-about-synthetic-motor-oils.html

do a google for more

 

[mchucker]

Well, sounds like you are on the right track . The gauge kit I installed on my 3813 was a simple Harbour freight automotive 3 gauge kit. The oil pressure gallery was in the same location as yours, it had a small plug that unscrewed . Amazingly, the provided oil gauge screwed right in. (by the way, i have 25psi at idle and 45-50 at operating speed) The temp gauge I installed in the overheat probes location on the bottom of the radiator. ( a less than ideal location for accuracy) I show 160 degrees on the gauge in the installed location. The temp overheat sensor was not working so thats why I put these gauges on. I look forward to hearing if you set up works, I may want to try it despite my electrical ignorance.

Chuck in Alabama

 

[Dave4514]

The relay circuit works and will allow the engine to start quickly and will shut down if the pressure drops. I am not completely happy with my circuit. The LED idiot lamp stays on all the time. It looks like the "Kill" wire has enough AC junk voltage on it to cause the problem. I measured about 5 volts AC. This kill wire coming from the ignition coil will need to be an open circuit ( no idiot lamp ) with the engine running. But all is not lost. I removed the lamp and plugged the hole with a black plastic plug. In all honesty I found that looking down at the idiot lamp was kind of a pain while mowing as I had to remind myself.

Here are the details on wiring the relay.

And here is the box with the relay stuck down with some silicone glue.

To get to the Kill wire I removed the black sheath that holds several splices. The wire comes from the ignition coil and uses a single round connector. Not wanting to damage the harness, a jumper was made to connect a new wire.

And here is the finished wiring with the relay box on the lower right. As you can see I made use of another jumper to tap into the solenoid wire and attached the ground to a screw used by another ground wire.

I will clean up the wires and use tubing to protect them from damage, but for the pictures I left them exposed.