[woodpecker41]

I have 6 or 7 of the Predators or the earlier Greyhounds and they are all alive and well and some at this point are 10+ years old. Roger

 

[btrukr]

The one I'm replacing is only 500 hr old, I don't think that long life. The reason I though about a remote filter is to increase the oil capacity and slow it down in the filter for better filtration and cooling of the oil

 

[.40370]

The one I'm replacing is only 500 hr old, I don't think that long life. The reason I though about a remote filter is to increase the oil capacity and slow it down in the filter for better filtration and cooling of the oil

Why are you replacing an engine that should run for 2000+ hrs with a Chinese knockoff engine when your Onan only has 500hrs on it? What is wrong with your Onan?

Jared

 

[btrukr]

Jared: The cam timing is jumping around, will run for 5 mins then start hanging the intake valves open @ TDC and then blows gas back thru the carb. I've priced gaskets, cam gears and cam and lifters. It wasn't cheap, then the motor has to come out to service it, as well as it's flat head not OHV. I have a 83/318 with 980 area on hours and I wouldn't pull it as it runs perfect. I bought the one with engine problems, with one head off, being told it needed a headgasket. I'm afraid of what I'm gonna see when I open the case, as I don't trust the guy I got the tractor from. I keep finding problems that don't jive with the story I was told. I gave 400 for a low hours tractor and want it to run

 

[.40370]

Jared: The cam timing is jumping around, will run for 5 mins then start hanging the intake valves open @ TDC and then blows gas back thru the carb. I've priced gaskets, cam gears and cam and lifters. It wasn't cheap, then the motor has to come out to service it, as well as it's flat head not OHV. I have a 83/318 with 980 area on hours and I wouldn't pull it as it runs perfect. I bought the one with engine problems, with one head off, being told it needed a headgasket. I'm afraid of what I'm gonna see when I open the case, as I don't trust the guy I got the tractor from. I keep finding problems that don't jive with the story I was told. I gave 400 for a low hours tractor and want it to run

Great price for a great tractor...... That is a pretty peculiar problem you are having with it......

If I may throw out an idea as this was something I discovered recently on a different engine but it had the same symptoms...... Check the valve to tappet clearance if you have not done so already. The issue that I was having is that once the engine ran for a few minutes the valve clearance got so tight that the intake valve was not closing all the way. I pulled the valve and ground the end of the stem to get the right clearance and now it runs great.

Not sure why the valve clearance was so tight to begin with but had a theory that the valve seat may not have been seated in the block properly from the factory and the repeated heating and cooling cycles along with valve action caused it to push further into position and this was causing the intake valve to not close all the way once the engine was warm. It was a Kawasaki engine, but it was also a flathead.

IMHO, if that engine is truly a 500hr engine I would explore all avenues within financial and mechanical means to make it run properly. Once you factor in the cost of the Predator engine, spacers, adaptors, modifying the exhaust, the wiring, etc, etc, you are well on your way to having your Onan fixed and running. One other thing to think about is that remanufactured Onan engines are available for $1500 with core. Might seem like a lot but you are saving a lot in the process. It is a drop in and go engine....... no muss, no fuss.

Jared

 

[shady]

Do you have a Predator 670 in hand? They have: oil filter, oil cooler, low pressure, and almost two quart capacity.

 

[btrukr]

Do you have a Predator 670 in hand? They have: oil filter, oil cooler, low pressure, and almost two quart capacity.

Yes sir, that's what the book says. I just got thinking of ways to help it, I mow 6 acres and it will be wide open as fast as possible. I'm having a problem figuring where it shall go too.

 

[btrukr]

Great price for a great tractor...... That is a pretty peculiar problem you are having with it......

If I may throw out an idea as this was something I discovered recently on a different engine but it had the same symptoms...... Check the valve to tappet clearance if you have not done so already. The issue that I was having is that once the engine ran for a few minutes the valve clearance got so tight that the intake valve was not closing all the way. I pulled the valve and ground the end of the stem to get the right clearance and now it runs great.

Not sure why the valve clearance was so tight to begin with but had a theory that the valve seat may not have been seated in the block properly from the factory and the repeated heating and cooling cycles along with valve action caused it to push further into position and this was causing the intake valve to not close all the way once the engine was warm. It was a Kawasaki engine, but it was also a flathead.

IMHO, if that engine is truly a 500hr engine I would explore all avenues within financial and mechanical means to make it run properly. Once you factor in the cost of the Predator engine, spacers, adaptors, modifying the exhaust, the wiring, etc, etc, you are well on your way to having your Onan fixed and running. One other thing to think about is that remanufactured Onan engines are available for $1500 with core. Might seem like a lot but you are saving a lot in the process. It is a drop in and go engine....... no muss, no fuss.

Jared

Jared: I tried to adjust the left intake and the adjuster is all the way compressed, I think it's been hot and maybe streched it in the stem. I'd sell it if someone needed a complete core or engine

 

[shady]

Get John Lang's firewall kit. That should keep your engine cool. Most run WOT when mowing. SEW kits for Honda and Vanguard used 3/8 inch adapters and that is what I used.

 

[btrukr]

I lifted mine 1.5"s and that left us with a 92" drive belt for the mower. I also used a clutch out of a 140 because it's 1". I ordered a muffler from small engine warehouse, had to change the clocking on the pipes that bolt to the heads, but it's a bull in a china house. well worth the work to change it

 

[dapetik]

I'm new to the forum and about to pick up a late model 318. Owner says it smokes a lot, hoping it's just aplugged crankcase filter. If not I'll be re-powering. Did anyone ever get a better solution to the muffler? Welding is the only thing I can't do....

 

[tadowler]

I'm new to the forum and about to pick up a late model 318. Owner says it smokes a lot, hoping it's just aplugged crankcase filter. If not I'll be re-powering. Did anyone ever get a better solution to the muffler? Welding is the only thing I can't do....

Honing and new rings might be a good interim step and these engines are relatively simple to work on.

Sent from my VS986 using Tapatalk

 

[gabby_in_wis]

Todd, I am new to this thread. I am not going to read 24 pages of text to catch up on Chinese dime store engines that you cannot get service parts for. I am assuming you are saying the original Onan engines are rebuildable and I absolutely agree with that being the resolution. I don't understand members wanting to install an engine that is maybe cheaper at time of purchase but has no history of longevity, robustness, and serviceability. If you need a replacement engine spend the money and get a Briggs. They are a known American company. Their engines may well be foreign made but everyone should be familiar with the name Briggs & Stratton. I would guess there are a large number of members not subscribing to this thread that could not tell you where to get a Predator engine or where it came from.

Does Harbor Freight supply service for these engines? Local small engine repair shop cringes when one of these engines is brought into their shop. Definitely a thread for "let the buyer beware".

This is my 2 cents. I'm gone ... Gabby

 

[CaptPete]

I'm wondering why you lifted the engine by 1 7/16 inches? If you dropped it right down to the frame it looks like things would fit. It's not necessary to have the driveshaft perfectly level, you have 2 single carden U-joints on the shaft and the needle bearlings get lubricated better if the joints move at least a bit. If it turns out that you do need to re-work the muffler, I'd suggest saving the mounting flanges and the muffler body if it isn't oversize and bend a couple of pipes to fit and weld it all together. If the muffler is too large, the Small Engine Warehouse has a generic muffler body that you can use, just add your pipes and mounting flanges.

 

[CaptPete]

I'm new to the forum and about to pick up a late model 318. Owner says it smokes a lot, hoping it's just aplugged crankcase filter. If not I'll be re-powering. Did anyone ever get a better solution to the muffler? Welding is the only thing I can't do....

A muffler shop could easily do the pipe & bracket modifications to make it all fit. A smoking Onan isn't something I'd be much interested in except maybe for parts. Borrow or rent a compression tester and see what the compression is on both cylinders, anything less than about 75 psi is pretty much ready for a complete rebuild or scrap heap. Re-engining isn't as complicated as it may seem and there are quite a few write-ups on using various engines so it's almost like putting mechano set pieces together.

 

[jfh9026]

It isn't just the crank has to be level, but to use all the original belts, etc, you ligne up the centerline of the crankshaft to match where the old centerline was. Trying to buy Onan parts, or find someone willing to work on them anymore is a major issue.
If you costed one out in your area where someone will do the work, it might not cost out the same for someone else who can't find or have someone work on it for them.
Sooner or later, ONAN used parts will be non existent.
Next best thing is a repower, take your pick, they all have things you have to do to each one of them to replace and Onan. Good luck to anyone who has the courage to repower an Onan. Good luck to the next owner who has to put up with a repower that isn't done wisely.

 

[CaptPete]

It isn't just the crank has to be level, but to use all the original belts, etc, you ligne up the centerline of the crankshaft to match where the old centerline was. Trying to buy Onan parts, or find someone willing to work on them anymore is a major issue.
If you costed one out in your area where someone will do the work, it might not cost out the same for someone else who can't find or have someone work on it for them.
Sooner or later, ONAN used parts will be non existent.
Next best thing is a repower, take your pick, they all have things you have to do to each one of them to replace and Onan. Good luck to anyone who has the courage to repower an Onan. Good luck to the next owner who has to put up with a repower that isn't done wisely.

The crank itself will be level if it's bolted to the original mounting plate in the frame, the newer engines, as you've found out, are built with the crank lower than the Onan was/is (it's still used in new generators). Not lifting the engine will affect the driveshaft angle, but not outside the U-joint capabilities. In my opinion, the only reasons for lifting the engine would be to provide clearance for things that can't be reached or otherwise moved (oil filter for example but this can be fixed with a remote location kit). Belts sizes are not critical to the tractor's operation and are the easiest and cheapest to change with no adverse effects. Lifting the engine just to put the crank at the same level as the Onan was can give you some major rework tasks such as a new hood design or conversely, changing the exhaust and air intake systems.

I'm well aware of the stumbling blocks involved in using different engines - I've re-engined one of my 318's (with a 23 hp Vanguard) as well as several other vehicles (cars & jeeps), some of which I still own. The 318 re-engining has an additional challenge that you may or may not have yet addressed and that's "which clutch to use". It took me a while to figure out the implications of using the OEM John Deere clutch (it's a modified Ogura clutch) or a new clutch that fits the new engines PTO shaft. Much of this is written-up in my thread on the subject. There's also a lot of other help on this site to help overcome some of these challenges - much of which saved me from many mistakes and a ton of work.

 

[steve770]

I wanted to add this update since I have been running a predator 22hp in my 1986 318 for a few years.
Started having trouble with hard starts. I could get it to kick over with starting fluid.
Ended up installing a $14 electric fuel pump.
I removed the main/aux fuel selector and put a toggle switch there to activate the pump.
It acts like a primer. I turn it on for a few seconds before starting and then turn it off.
Engine still running well.

 

[bighorn2006]

I don't know how many amps the Harbor Freight Predator 670 puts out but I doubt it is anywhere near 20. Mine have been able to keep the PTO engaged and restart the engine with no problem. In addition to the PTO I have NO lights, radio, or other electrical devices. It is a bare bones daylight mowing machine.

I have been following a golf cart forum that Army mentioned a couple of years ago and someone there added a 1wire GM alternator straight to the battery via the starter without changing the in place wiring system. Waiting to see how this does. At least waiting as I have wanted to add an alternator for several years but have yet to get it done.

Will have to learn mig welding so I can mount the cut down muffler so the hood will fit - then will have a place to mount the lights, computer, and gps system.

Have you had any issues yet with the amps? I'm installing a HF670 in my JD312. About all I have is PTO.

 

[tmac58star]

This thread is 3 years old...