OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Honda Engines GCV160 Funny Valve Lash

Guys:

First, thanks for this great forum. I am very impressed with the expertise here! I have a valve lash issue, and would appreciate any help folks can provide.

I removed the head cover from my GCV160 and discovered that at TDC the intake valve lash was over 0.040". Exhaust measured at 0.006". I am uncomfortable simply setting the lash to spec and putting the machine back together, and would appreciate everyone's input.

Background: I bought a new Karcher pressure washer equipped with the GCV160 engine. It now has 40 hours on the engine. Changed oil at 5 hours. Oil level good. But one day the engine would not start. Good spark, but discovered zero compression.

So I pulled the head cover. Discovered the intake valve was not moving freely. Valve stem covered with goo that looked like typical gasoline varnish. My fault. I suppose I left gasoline in the engine and it got stale.

I sprayed carb cleaner on the stem and the valve immediately began to move freely. Finger over the plug hole indicates compression is now there. But there is huge clearance between the intake valve stem end and the rocker arm of 0.040".

I wonder what might cause the funny lash readings. It sounds like there is metal to metal contact so the intake valve appears to be seating. But something is not right. Could the rocker possibly be bent? Any ideas and guidance would be greatly appreciated.

Thanks, Bill

Hi Bill, only 2 things it could be, valve seat moved or as you say bent the rocker arm. Always going to be hard to tell if the arm is bent, you would never be able to see 0.040" without some good measuring equipment

G'day Bill and Norm,

It seems that these engines are a bit prone to valve gear problems, even to breaking rockers. Past thread on this topic is HERE .

If it's had a stuck valve, for sure a bent rocker is possible. As Norm says, there's no easy way to check if the rocker is bent. But if you can adjust the clearance to spec, it should still work OK.

Norm and Gadge:

Thanks much for the input and suggestions.

I had enough room to adjust the intake valve lash to spec, so have done that. So I suppose that if I have a bent rocker arm, I should be good to go.

But then I got to thinking about the possibility that the rocker arm is good and that the valve seat has been pushed down by the 0.04". If that's the case, then who knows what will happen when I fire up the machine.

I used a depth mic to measure the stem protrusion from the head for both valves and the measurements were close. But who knows what that means?

A new rocker arm will cost me $US 5.00. So being an overly cautious type, I am going to order a new one and see if the existing one is indeed bent.

If the rocker arm isn't bent, then I am going to go ahead and fire up the machine anyway. I'll have a second rocker arm if needed.

It'll take 4 or 5 days to get a new rocker arm. In the meantime, I would appreciate any additional input. Especially if my thought process is wrong. Like should I dismantle the machine and inspect the valve seat?

Thanks again! Bill

Bill I wouldn't get overly concerned and in reality I doubt the valve seat has moved, can never completely rule out everything. Enfields often suffered from for this but the only problem it caused was the motor wouldn't run, no other damage. Bent valve stem wouldn't give you 0.040"

If the engine has 40 hours on it, how old is it. Honda have a pretty good 2 year domestic warranty, perhaps you can have it repaired under warranty ?

Paul:

I bought the machine in 2008, so it's probably out of warranty. But who knows, maybe they'll listen since it has only 40 hours on it. And it looks brand new.

I'll give it a whirl. Thanks for the suggestion!

Bill

I already received a new intake valve rocker arm in the mail today.

Recall that I had previously set the valve lash to spec with the old rocker arm, which I thought had been bent.

So I took the old one off, replaced it with the new one. And it became immediately obvious that the old rocker arm was not bent.

So I don't know why I have developed a mysterious 0.040" valve lash. I am going to make up a temporary paper cover gasket, put the machine back together, fill it with oil and see what happens.

It the engine starts, I imagine it will kill itself in short order. I'll be back in there either replacing a broken rocker arm, resetting the valve lash, or who knows what else.

I'll report back tomorrow.

Just my 2cents on your issue.i have seen this happen twice at work on this model.was working fine,then would not start ,and no comp ,with excess clearance.freed up valve to get it to fully return and seat,but would stick again.after removal of head, I found VERY small galling inside valve guide,that was causing valve to intermittently hang up.cleaned problem area up,never had issue again.

One thing to check seeing it has this 0.040 clearance, does it have compression, if not probably as Pope says

Thanks Pope and Norm. After I freed the sticky valve, got good compression. If the machine now starts and dies again, I'll tear the machine apart and see what's going on, looking closely at the valve guides.

Yes,certainly sounds the same problem mate.As stated ,if problem re occurs remove head and offending valve,thoroughly check guide inner and valve stem for ANY galling or build up

Thanks again mates, for all of your help. I have just had a partial success.

I reinstalled the head cover and temporary gasket, filled the machine with oil, and fired the thing up. The following is what happened. Would appreciate your thoughts.

Are these symptoms consistent with what you're thinking is the problem? Or could I have another unrelated fuel delivery problem?

1) Closed choke
2) Pulled the started rope 10 times - nothing
3) On the 11th pull, a whimper. I'm excited
4) On the 12th through the 30th pull, it runs for 2 seconds at about half speed, then dies
5) On the 31st pull, it keeps running, though at half speed. Now I'm really excited
6) I let it run for 2 minutes for warm-up, then close the choke. Stops firing. I immediately open the choke again and it resumes running, again at half speed
7) I repeat #6 several more times and the same thing happens - the machine will only run at half speed, and dies when I open the choke.

Is my next step to pull the head and find out what the valve guides, valves, and seats are telling me?

Thanks again, mates. I truly appreciate the help.

Regards, Bill

Bill, 37 pulls, you must be exhausted, I would have given up way before that.
The fact it WILL run at half speed indicates the valve is closing and the fact it will die with the choke alteration indicates carby problem. I'm tipping a jet issue

Hi,did you make sure valve clearances were in spec before putting rocker cover on? If so,what do they read now? If they were in spec,and if you check now and they still are,I would look at a possible blocked jet scenario.but you need to check the valve clearance first.when it did run,was it popping back through carby.(like a hiccup)

I am certain you would not have a chance in hell with warranty on a 8 year old machine.

Thanks, Pope.

Yeah, I set the clearances to spec before I started the machine.

No popping through the carb when running. Pretty smooth actually - just an anemic, wimpy speed.

So my next move when it gets light here, is to pull the cover and check the lash. Hopefully it will be 0" on the intake side, indicating trash is clearing from the seats, guides.

If not.......

Thanks, NormK:

Yes. Had I not gotten at least a little encouragement from the machine as I flailed away, no way I would have continued.

When I ordered the rocker arm, I also ordered carb gaskets just in case a carb cleaning was needed. So after I check the lash this morning, that should enlighten on whether I have a valve, or fuel delivery problem. In theory.....

Thanks again, Bill

Bill is there any chance there is a blocked filter or something blocking the airway?

Thanks, NormK. I pulled the filter and air cleaner and can see through to the choke butterfly. So all appears clear.

I pulled the head cover this morning and found the lash settings still to be right on spec.

So my next move will be to pull the carb and see if there is anything strange there. If not, it's off with the head.

Thanks again for everyones' help. I'll post again shortly.

Regards, Bill