WD suddenly running rough

tinknal

New User
I was cutting wood in my woodlot this past winter and my WD very suddenly began running very rough and very loud. This is different than a plug wire coming loose, which happens occasionally. With one plug wire off I can still skid logs with this tractor, right now it does not have enough power to move itself. The first thing I did was check the fuel line and sediment bowl, all good. The noise is a loud knock. There appears to be soot where the exhaust manifold meets the engine near one cylinder but I do not know if that is new. Any ideas?
 
Check the oil and water levels. It may be eating a rod. You can try feeling heat at the 4 exhaust ports to see if it's one cylinder.
AaronSEIA
 
Are you saying that your tractor seems to be firing on only two cylinders, or is it running on all four with a loss of power, or do you mean something else?

It sounds like you do have an exhaust leak, but that shouldn't lose power appreciably. A head gasket leak could account for a noise, a loss of one or more cylinders. Is it possible the culprit is the head gasket? A compression test of all cylinders would tell you a lot quickly, or at least rule out a lot of possibilities.
 
Would a head gasket fail that quickly? It was like turning a switch. I'll check compression tomorrow.
 
I would check the manifold real close for cracks or holes. If the knock sound is up by the manifold and not down by the pan it sounds like a manifold exhaust leak. I have had a manifold break thru from the exhaust into the intake. that will cause two cylinders to lose power. I found it by blowing compressed air into the intake and it was coming out the exhaust. I then sawed the manifold into sections to show the problem.
It may not be your problem but something to check.

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(quoted from post at 17:44:52 05/05/18) I would check the manifold real close for cracks or holes. If the knock sound is up by the manifold and not down by the pan it sounds like a manifold exhaust leak. I have had a manifold break thru from the exhaust into the intake. that will cause two cylinders to lose power. I found it by blowing compressed air into the intake and it was coming out the exhaust. I then sawed the manifold into sections to show the problem.
It may not be your problem but something to check.

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The noise is definitely coming from the top. I will check this out.
 
I have seen where the distributor cap has cracked and the spark was all going down the crack. If it fires on the wrong cylinder while coming up on compression it would kick back and be a loud knock. Just thinking. Let us know what you find.

Steven
 
I finally got around to checking compression. No compression on the second cylinder from the front. Sounds like bad news.....
 
Keep hope, you can't know it's not just a valve issue until the head comes off. Possibly just the exhaust valve stuck slightly open due to a chunk of carbon breaking off. I paid less than $100 to have the entire head redone, valves ground, surfacing and clean up. I would think a single valve may be much cheaper. Maybe that's all it is if you didn't have excessive crankcase pressure.

I don't think I'd run it further just in case it is a valve and currently not damaged. You may be able to clean it up at home with just lapping, then it's just the price of a head gasket.
 
No compression on #2 cylinder, cylinders are 1,2,3,4 from the front going to the back. Could be a number of things. Stuck valve or bent push rod, or hole in piston or broke rod or a blown head gasket. I would start by pulling the valve cover off and have a look see at the valves. If they look good I would pull the pan and have a look see from the bottom. Cheaper to pull the pan then it is the pull the head off. With the pan off you can see the rod and the piston.

I have a MH 30 engine that all at once it died and the dip stick went flying. When I pulled the head off #2 piston was gone as in it just plan broke apart and drop down into the oil pan
 
Finally tore into the WD today and discovered the problem. This object was stuck in an intake valve. It is brass, about 3/8 of an inch long by about 1/4 of an inch wide. It appears to be 2 parts. It looks like a small brass pin with a rounded brass disc slid on to it with the ends of the pins mushroomed over. Seems to me that it either had to come from the carburetor, the air assembly, or the head itself. Does anyone know what it is?
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That's amazing. I can't see how something that large would even fit in there. I doubt something like that could get through an oil bath air filter.

It doesn't look like the ones I have, but perhaps the bypass from the choke plate? Hopefully someone will know what it is.
 
So the valve is still sealing well? Did you run some solvent in the port to see if there was any leakage around it. If you have the head off, it's the time to check that, and it will make sure your compression is good when you put it back together.

It would be fascinating to identify where it came from too. I still amazed it fit in there.
 
Yeah, the head is off, need new gaskets before I replace it. There doesn't look to be any damage to the valve. What exactly do you mean by "running solvent in the port"? BTW, do you have a resource that shows head bolt torque?
 
When you put a compatible liquid into the port (with head sitting on it's side so it pools around the valve), it will seep out the face of the head if there are irregularities in the valve seating. It tells you whether you need a grind or at least lapping to get a good seal and the compression will stay up. People used to use gasoline, but that practice is discouraged nowadays due to the flash danger of gasoline.

Here are a couple of shots of the area I found in the WD/WD-45 service manual. No experience personally with a WD head so use at own risk, 90 sounds a bit high as a low point for the torque, but certainly close to what I'm used to. Others may provide better information. I am also not familiar enough with the WD to say if this is necessary or not, but on some head bolts that protrude into the water jacket, it's common to use thread sealer (e.g., Form-a-gasket Thread Sealer is one such product).

Hopefully someone who has actually worked on a WD head will confirm or correct this information. I have a WF now, but have not worked on it yet.

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I'm not an expert in sealants by any means, but I have heard that you should be cautious with Teflon tape. Too much and you may undertorque and otherwise, you could overtorque.

You also have to watch out because anything you use, if it finds it's way into the flow, will clog the radiator.

I believe the correct way to do it, is use new head bolts on very clean holes and trust the gasket to do it's job, but in the real world, that doesn't seem to happen. I used to use that dark gray #2 thread sealer very sparingly and not run it on the ends of the bolts. A fellow who does Model Ts, turned me on to the white thread sealer which I tried this time. I was told it will not impact the torque much, and is non-hardening so it will not likely clog the system if a little gets away from the threads.

I probably shouldn't have mentioned sealing them. It's just a paranoia I have, others torque them dry I imagine. Study up on Teflon tape and sealers, for that application before using it. You can form your own conclusions, there is likely no one right way to do it. Here is a photo of why I was concerned with sealing. The bolt on the right is similar to the ones that came out of both tractors I've recently worked on. I'm just guessing they were bathed in coolant all their life. The one on the left is a relatively new one I used to replace the other. It just looked to me like it would be better if the bolt were not bathed in coolant.

Wait and see if others have an opinion on sealers on head bolts, there are experts here on the forum who've done a lot more engines than I have.


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Thanks. The head bots have the nut at the top so no replacing them, just the manifold bolts, and three of them unthreaded at the nut rather than from the block.
 
I just had problems sealing the manifold studs on the D14. Filled it with antifreeze and it dribbled all over. Had to use sealer.
 
I took a close look at the #14A permatex thread sealer while I was up in the shop, it has teflon in it. If Permatex thinks that's okay, I'd bet it's okay to use teflon. I suppose there might be logic to not going crazy on the number of wraps with the tape type.
 

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