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Should I Pull the Head?

6289 Views 24 Replies 9 Participants Last post by  X500Driver
I'm working on a Kawasaki FB460V single cylinder in a JD 160. This mower hasn't started for probably 2 years or more, but I've kept it just the same. I bought the X500 shortly after flipping the 160 on my hillside. After throwing a few parts at it that didn't make any difference I went through the shop manual troubleshooting guide. I have good spark.

I have what I think is good compression. I don't own a gauge so I used the manual instruction of rotating the flywheel counter clockwise and judge the rebound. First attempt was not very much rebound. I retorqued the head bolts to specs - they were loose. Now much better rebound and my finger over the spark plug hole feels a lot more compression too.

I partially went through the carburetor to make sure the main and pilot jet was open and float was set correctly. I did not completely disassemble though. The main had no debris, but I noticed there was not a through hole on the pilot jet - just 2 side inlet holes and one at the bottom.

When I drain the gas from the float cup it is strong gas smell and no indication of moisture. Fuel is flowing from the pump to the carburetor. The filter has some sediment in it, but is not clogged since the fuel is flowing. I have tried starting fluid to see if that would help.

The engine will crank nicely, spins ok on a full battery or jump, but just will not catch and start. It does seem to spit a lot of fuel back out of the carb when it is cranking. Spark plug is wet after cranking so it is getting some fuel, but I really can't tell if it is getting enough or in the right air mixture. I'm about tired of not getting any improvement.

I know the gas may be a little old, but it was treated and still smells strong. Maybe I should try a "flash" test with a small amount to see if it will still burn tomorrow. However, I am becoming more suspicious of something internal, especially since starting fluid doesn't seem to help. Perhaps a valve or something. But I don't hear any strange mechanical noise when I'm cranking so I don't think it is a valve spring or such.

If I pull the head, what will I see that might be a cause of not starting? Or, am I going to have to go much deeper in the engine, which I'm over my skill level already? Will I need a new gasket or can I reuse the old one for now?

I'd appreciate any advice. These things never work out without talking it over with friends. Thanks.
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Test the compression and give us a number, a compression tester will be as cheap as a new head gasket, but you will be able to use the compression tester again in the future.

It is not uncommon for that engine to lose intake valve clearance. Pour a little oil into the air intake to seal the valve and get the engine started. I don't know the Kawasaki spec. in the clearance, but I've set them at .007-.008" with good results. The engine may also not run well with too little clearance, in addition to being hard starting.
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Too little valve lash as rscurtis alludes to will also cause the fuel reversion problem which you describe, as will an intake valve seating poorly. If you discovered head bolts to be loose, it's a virtual certainty that the head gasket seal has been compromised, & that the valve lash is out of spec. By all means, check the compression against factory spec. These newer overhead valve engines aren't anywhere near as forgiving as the old "flatties" that you may have been used to. The replacement parts for that Kawasaki are gold & the man behind the counter is not your friend.
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These newer overhead valve engines aren't anywhere near as forgiving as the old "flatties" that you may have been used to.
Providing that the engine was never replaced, a Kawi FB460V in a John Deere 160 IS A FLATHEAD ENGINE, NOT OHV.

Well bad news I suppose. Gas out of the float cup ignited and burned just like the week old stuff in my gas can. So, I went to Harbor Freight and picked up their compression kit on sale.

Hooked it up and absolutely no reading. Nada, nothing, needle didn't move. Just to check, I put it on the X500 and got 80 pounds cold. So the gauge works.

I suppose I could pull the head and replace the gasket and just see if that makes any difference. Otherwise I need to find a repair shop with the tools and knowhow to get inside the engine or think of a new engine. But this afternoon I'm pretty well resigned that she won't be running next week when I needed her.

Thanks for your advice - it was most helpful.
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You may have an intake valve stuck open. You said it spit fuel out of the carb and now you are not getting any compression. To me that is the most likely problem.
You now can remove the head as either way you have confirmed you have no compression, when the head is removed confirm that the piston is moving, if it is which I believe it is, then check your valves. Providing you haven't lost a seat or one of them is stuck open then it is likely due for a valve job, you can test for this with a feeler gauge and the valves in the closed position.

Let us know what you find and we can advise further.

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I'm going to sleep on the next step. Do I need to drain the oil before I pull the head off?
If you want to remove the head, you can check the valve clearance while you're there. When the valves are closed, you should not be able to rotate them. If you cannot find a spot where the valve will not rotate, you have the clearance problem, which on an FB460V, you can fix in half an hour. That is a very durable engine and most likely will not need a replacement, which brings its own set of problems, as the 460 is not made anymore.
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You do NOT need to drain the oil to remove the head, simply remove the shield if it is still there and run the head bolts out, the head should pull right off and you can begin to check for your problem. Very simple process really.

Well curiosity got me. I pulled the head. Combustion chamber and valves are coated in carbon buildup. Pretty nasty. The valves seem to work properly. Both open and close and I can not see any broken springs or anything sticking. A small amount of oil seeps when the piston reaches TDC so at least the oil ring is working, but I can't see any of the other rings.

My next step is to find the flatest thing I have to check the head for warping. The gasket had no obvious cracks or blowouts and seems to be in serviceable condition.

Should I try to clean as much of the carbon from the valve faces, piston top and head as I can? What's a good solvent for this task? I'm thinking a nylon bristle brush or a plastic putty knife so as not to scratch the metal.

Again, thanks in advance for the advice.
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Tonight I got the head cleaned up and checked for warpage. It is well within tolerances on my float glass which is the flatest thing I have. So I surfaced it with 200 and then 400 grit sandpaper.

The head gasket shows no obvious tears or openings, but there appears to be soot or burn marks near the edge where the exhaust valve is.

Question. Are head gaskets similar in function to a crush washer? Meaning that once they are torqued down you won't get the same seal if reused. I would like to get a new gasket, but if the old one is reuseable then I prefer to put it back together to get it running.
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You need to use a new gasket, but I think that you are missing your problem unless I passed over it, have you checked the valves with a feeler gauge to insure that they are closing?

use a new gasket. You said the head bolts were loose, the head gasket needs replaced.

And torque the bolts to correct torque and in the right order.
If the back of the valves have a heavy deposit of carbon it will restrict the flow.
From what I can tell the valves appear to open and close like they are suppose to. Once I get the faces cleaned up I'll check the seating with a feeler gauge to make sure they are seating and check the valve to tappet clearance.

My problem is I don't see how the valves can be adjusted as it sits. As I understand the manual I'd have to pull the valves, replace guides and recondition the seats, and do some grinding to get the right specs. That looks like bench work with the engine removed. Frankly, that is beyond what I had intended.
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Access to the valves is accomplished by removing the carburetor assembly (you can leave the manifold on the engine) and then removing the breather cover. Clearance is increased by grinding the base of the valve. Go slowly- once removed, you can't put it back. When re-installing the intake elbow, make sure it engages the crankcase breather fitting, or you'll have another problem down the road. Don't worry about the head being warped, just use a new gasket as others have suggested. I have worked on many of these over the years, even saw one dive into a swimming pool while running when the Bobcat clutch locks slipped into gear. It went right to the bottom. I changed the oil, replaced the air filter, and started it up, none the worse for wear.
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Thanks. I've pulled the breather cover, but pulling the valves is just beyond my skill level - not to mention a spring compressor. I'm sure they would need lapping too, so that is just too much for right now.

I sourced a new head gasket locally so I'll put it back together tonight and see what happens. If she runs then fine, if not I'll have to think on going deeper into the valves. The tranny is about shot again so it just may not be worth the cost.
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As John9001 said, make sure you torque the head bolts in order and to the correct torque. And, if you get it running, make sure you re-torque after an hours run time.
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