starting problems with 416-h

[benMA 1]

Hello All,

 

I recently bought a 416-H with an Onan P216 and I had some trouble starting it all along but recently it wouldn't start at all. I sent it off to the local repair shop and did a compression test and leak down test and he's recommending replacing both intake valves. He said he thought it had been running lean for a while and it burned up the valves. Two questions, does this diagnosis make sense and also, are there any good sources for engine parts like gaskets and valves? I see some online but I don't know if they're quality or not.

 

Thanks for any help!

 

[ri702bill 10,511]

Welcome!

 

1 hour ago, benMA said:

but recently it wouldn't start at all.

As in it would not turn over or it turns over but has no spark??

Both are common issues with well used Onans. How many hours on it??

There is a 9-pin wiring connector that corrodes internally; that creates high resistance and melts the terminals / shell.... Find it, separate the halves, and clean / replace it if it looks bad.

Second - Onan's with 1000+ hours tend to develop a valve seat issue. The seat becomes loose in its place and there is usually no permanent fix except engine replacement. 

A loose seat can mimic the bad compression or leak-down symptom diagnosis.

All said & done, you need to address the running lean issue before using it once fixed. Intake manifold leaks are rather common on Onans.... and are fairly easy to identify.

Bill

 

[benMA 1]

Thanks Bill,

 

I believe it is not an electrical issue since he said the compression on both cylinders was really low and the leakdown test showed a leak. It previously would crank and crank and eventually catch but it got worse and worse until it wouldn't catch at all. The reason I'm skeptical about his diagnosis is the tractor only has 400 hours on it. He is quoting me about $900 to do a full engine service (repair the valves and seats, flatten the head, new gaskets, etc.) but he is suggesting a swap with a new Vanguard 23hp for $2500 parts and labor. Obviously a big difference in price and I'm not sure what to do 

[lynnmor 8,198]

If the testing showed the intake valve(s) leaking, pull the head and try to determine if the valve seat is loose.  Sometimes a simple valve adjustment will fix it or go ahead and reseat the valves.  To do that valve service you would pull the valve and grind the surface that meets the seat.  You would also refinish the seat surface.  Download the Onan Service Manual to help you with that.  Once we know that the valves are correctly adjusted and seating properly we can go after other things if needed.

[ri702bill 10,511]

1 hour ago, benMA said:

he is suggesting a swap with a new Vanguard 23hp for $2500 parts and labor. Obviously a big difference in price and I'm not sure what to do 

The Vanguard swap is a rather popular one - but you've really got to have a tractor in otherwise excellent condition to justify the coin involved....

[953 nut 62,906]

14 hours ago, benMA said:

He is quoting me about $900 to do a full engine service (repair the valves and seats, flatten the head, new gaskets, etc.) but he is suggesting a swap with a new Vanguard 23hp for $2500 parts and labor. Obviously a big difference in price and I'm not sure what to do 

The majority of the $ 900 quoted is labor and there may be some unforeseen internal problems found once the teardown is done so the price could go up from there.  If you have the space, skills and inclination to do the job yourself the Vanguard swap would be he way to go. The price you were quoted includes about $ 1,000 of labor cost that you could put back in your pocket by doing a little DIY.