View Full Version : Need mechanics help for repair - Honda GCV160

04-22-2010, 08:36 PM
OK, let's start at the top. First, I admit a dumb mistake, so let's get that clear at the beginning. So, hanging my head in shame, tail between legs, let me get on with the problem.

The punch line: I need help with a broken timing gear.

A friend of mine spoke to me last Fall. He bought a pressure washer, albeit a small one, not of good quality, but thought to be adequate for his homeowner tasks. It is powered by a Honda GCV160 engine, pressure rating of about 2,500 psi, with flow of about 2.5 gpm. These specs may not be quite right, but you get the idea of the size of unit. He said the pump was broken. He asked if I thought a new pump could be found and mounted. I did some online research, and found one that was intended for a one-for-one replacement for the specific model. However, he did not make a decision about the problem.

In early March, he asked me again what I thought. In the end, we decided for me to get the pump, and I would get it installed. He is an outstanding cabinet maker (retired for many years now), but mechanically, he doesn't do so well. The job looked pretty simple and straight forward. I ordered the pump, and, after some delay, arrived.

Last weekend, I got his washer unit, and put it up on a table in my driveway (plywood sheet on horses). I unbolted the old pump. That meant the engine was completely loose from the unit. Three bolts fastened the pump, through the frame, and screwed into the engine base. There were no other connections (e.g. low pressure sensor). The pump is a direct drive, through a keyed shaft out of the engine. Perhaps this is how they are all done -- only one I've spent time tearing apart to some extent.

With the engine loose, and my single-handed attempt to get the new pump positioned in the right place, get bolts through the frame, and started in the engine base, I quickly found I was short a hand or two. Many failed attempts happened, and the engine was not tied down. The inevitable happened -- the engine fell off my table (told you "dumb mistake").

After more work, I finally got the three bolts through the pump, through the frame, and screwed into the threaded holes in the engine base. In reality, the replacement should have taken all of 20 minutes, but I wrestled with it more than one hour.

When the engine fell off, I did a quick examination. I feared the gas tank was the most vulnerable. In checking for damage to the tank, I found none. Also, the exposed stub shaft was vulnerable, but no damage to it either. I did notice that the OVC cover on the front had a ding in it -- just cosmetic damage to the cover.

I got it all hooked up the water, wand hose, etc, and tried to fire it up. No success in getting it started. The owners assured he he had run it late last Fall with no problem. After some doing, I found nothing wrong. The spark plug looked good, but when looking for an arc across the electrode of the plug when grounded, and pulling the cord on the engine -- no arcing across the electrode. This means no spark. Why?

My only conclusion was a bad ignition module. Why would the drop of the engine cause a bad ignition module? I did some research, and found one online. Also, I found a local dealer with one (didn't realize there could be so many choices in modules for a very common Honda engine). Apparently, the module is somewhat unique because of the shutoff switch connected to the module. I'm not sure how the GCV160 is used on the consumer lawn mowers.

I did an online search through parts manuals, but did not find the family number of the specific engine in question. Why? I wish I knew. I took the module number directly off the one mounted on the machine, not a parts manual.

I found a dealer with an ignition module late this afternoon. I wanted to replace the dinged up OHC cover, so I took it off. When I opened up the cover, I quickly discovered I had more than just cosmetic damage.

The timing gear had a piece broken off, the timing belt was off the cogged gear. When the cover got hit (on the drop off the table), the cover indentation hit the gear, causing the damage, and shoving off the belt.

Ouch! This started out as a pretty insignificant project, and now I have a damaged engine, and am unsure how to fix.

Obviously, I owe the owner his washer back in his garage, in working order. But, I now have a damaged engine that I'm unsure I can fix (many mechanics in the audience probably would consider this small stuff). Do I buy a replacement engine? Do I buy him a new pressure washer?

I see two issues. How to replace the gear? And, how to get the gear timed on the timing belt properly?

Here are some images. I may need another post to get them all included. I'm looking for some guidance on a couple of levels.

1. Why can't I find the parts manual online? I see a family number: 3HNXS-1871AK.
2. Is getting the old gear out difficult? I see a protrusion on the bottom, but am not sure how it is important for the gear. It is at the pivot point of the bottom gear.
3. Is there a repair manual online to give me guidance on how to get the timing belt mounted properly with regard to synch of the crank? The gear has lobes on it for activating the valves.

Anybody with some thoughts about helping me out of my stupidity? Thanks.

04-22-2010, 08:38 PM
Here are a couple of more pics. Included are the engine labels.


04-22-2010, 09:37 PM

Take a look on the engine block, There should be a flat area on the back opposite the head with the true engine numbers stamped in place something like this; GCV160A A2R,VIN# GJAEA-1000001 ....There should be no problem looking up parts with these.

You can look up/purchase parts here; http://www.boats.net/parts/search/Honda/Engine/parts.html

I have a old GCV160 at the shop, If I remember the bottom end took a dump but the top end is good. If you can find/post the numbers off your engine I'll double check part numbers on the cam gear I have, If they match you can have the gear/cover and anything else you need.

I'll have to look into timing this thing, I've only done one and it was a few years back so I don't recall how I did it (ole age)..... :rolleyes:

04-22-2010, 10:02 PM

Take a look on the engine block, There should be a flat area on the back opposite the head with the true engine numbers stamped in place something like this; GCV160A A2R,VIN# GJAEA-1000001 ....There should be no problem looking up parts with these.

You can look up/purchase parts here; http://www.boats.net/parts/search/Honda/Engine/parts.html

I have a old GCV160 at the shop, If I remember the bottom end took a dump but the top end is good. If you can find/post the numbers off your engine I'll double check part numbers on the cam gear I have, If they match you can have the gear/cover and anything else you need.

I'll have to look into timing this thing, I've only done one and it was a few years back so I don't recall how I did it (ole age)..... :rolleyes:

See that's what I like about this forum, guys liek Restrorob.

04-22-2010, 10:16 PM
Thanks for the response, Restrorob, ...

I thought I looked it over pretty well, thinking something should be on the engine, not just the shroud. I will look again. Perhaps my eyes were crossed from the frustration of doing a stupid thing -- not the first time, won't be the last.

Yes, the designation you offered as an example is exactly what I saw in the online places I looked.

04-23-2010, 01:06 PM

If you remove the recoil assembly and raise the flywheel cover up there will be a pad just to the left of where the decal is, That's where they hid the numbers.

If you can't find the three letter type number as I couldn't on this one I have, Post the other number and I'll call my supplier and get them.

I've got the coil/cam gear/valve cover and a good timing belt if needed....

04-24-2010, 09:11 PM
Restrorob, .. thanks for that information. However, I spent much time looking for the numbers. I finally found them, on the vertical plane. I was looking on the horizontal surfaces. Also, the aluminum had a white powder over the surface, and it took some rubbing to get them to come clean.

I have posted a couple of pics below so that others can easily learn where to look if the need arises.

After I got the number, I spent time online to learn more. This engine is an N5AF, and is widely used on pressure washers and log splitters. If I understand the way boats.net arrange their information, it is a pre-1997 engine. The number of variations on the GCV160 is beyond comprehension!

I did find a place with a new engine, and was tempted to place an order and be on the safe side. But, ... my gut tells me that somehow I can get this thing fixed, albeit weekender skills. After looking closely, and knowing this is the same kind of arrangement, and materials, I am amazed that my GCV190 on my Honda HRX217 is still running!

I took the numbers down, and headed for a dealer. After much time at the counter, I learned they had none of the parts. I wanted the dinged up cover, and the lobed gear pulley. I also wanted the clutch plates for the BBC on my HRX217 as well, but didn't have them either.

I was really distressed because getting this fixed was on my list for today. Next week is a very heavy mowing schedule, and the weather is iffy for Monday. So, today, ... this was it. I called two other dealers, no parts in stock.

I came home and ordered all the parts for the GCV160 and HRX217 from boats.net (Outdoor Network, LLC). So, thanks for your offer, but I will wait for the order to come from FL. The HRX217 clutch parts are not needed -- just feel the clutch isn't coming to grip like it used to and the adjustment is at the end of the line.

While I was changing oil in my HRX217 tonight, I tried to take off the numbers of the GCV190 engine on that machine. While the numbers on the GCV160 became pretty clear after some rubbing, the 190 numbers were nearly impossible to read. I ended up with a running a lead pencil over the markings, making the numbers/letters more clear. Also, I shot a digital pic from a slight angle, in order to get some use of shadows to make them appear better. You can see the engraved numbers/letters on the 160 -- pretty clear, once one knows where to look (ha, ha), and gets the surface clean.

I am still at a loss on how to get the shaft out in order to replace the gear. I see the shaft penetrate the lower part of the case, with apparently an O-ring seal. The shaft is not tight in the holes, rather rotates pretty easily. I see the top from the pivot point above the gear. Maybe it just pulls out with some force, ... not sure. The top protruding out the bottom is odd shaped, about 1/4" long, but with half of the shaft milled away. I see nothing mechanical holding the shaft in place.

Yes, I still don't know how to time it either with the new gear.

I did spend some time looking for online service manuals, but did not find anything. Well, ... not quite right. I did find one for a $34/yr subscription fee for downloads. I'll keep looking.


04-24-2010, 09:47 PM
I will take a shot at explaining this, its kinda tough to explain, a lot easier to show. You will need to split the crankcase to time it properly. There are 2 lines on the cam gear, they both need to be just visable and parallel with the case (for this part you just need to have the valve cover off, there is also a mark on the crank shaft that lines up with a mark on the block. when everything is lines up pop on the belt and you are good to go. Like I said, its tough to explain but easy to show. If the timing belt is still on you should be able to replace the gear without splitting the case, just line up the marks as stated above then mark the belt and gear with a crayon, and put the same mark on the new gear. Remove the old gear keeping tension on the belt so it doesnt move on the crank gear, then pop the new gear in lining up the marks. (I have done this once and it saved a lot of time).
BTW the came gear shaft just slide out once the OVC cover is pulled off,

04-25-2010, 10:53 AM

Here's a PDF owner's/service manual, The bottom of page 3.4 explains/shows how to set timing.


The cam gear pin must be positioned with the cut-out facing up so the tang on the valve cover can hold it in place.

04-25-2010, 08:05 PM
mower ... and Restr... -- thanks very much for your additional input. These posts help clear up my immediate questions.

After looking more closely at the cover, I see a small flap on the bottom edge. It must key up the the bottom of the timing gear shaft, so that it does not drop down, or turn. I will not try to extract the shaft until the new timing gear has arrived.

Restro ... the link to the manual, albeit more languages than I can use, is the good information I was needing. Also, mower... your comments will be helpful when the time comes. I'm sure it will make more sense when fitting the new gear in place, and I see the markings.

I'll keep you posted on progress after the parts arrive. Thanks again -- great help here!

05-16-2010, 09:25 PM
Well, it has been a long couple of weeks. I placed an order for a new timing pulley, and a new valve cover. It took more than one week for the first order to arrive. The timing pulley was right, but rather than the cover, they sent me a spark plug!

After a couple of e-mail exchanges, a replacement order was processed. So, another week, or more passes. Last week, mid-week, the cover arrived. I did not have time to deal with the problem until late today.

Good progress, but not quite there, yet...

I knew the install wasn't much work, but getting it timed right was the key. One page from the European manual of the link provided by Restrorob was the pivotal information.

The pin on the old pulley merely pulled out from the bottom. It came out easily, permitting me to take out the damaged timing pulley. The belt had been pushed off in the accident, so there was no saving of timing position from the old one.

The new pulley installed easily. The pulley has two marks on the underside. They are alignment marks, just as the post above says. The intention is to get them aligned with the surface against which the cover is bolted. (I know -- all easy stuff for the mechanics, but new stuff to those of us who don't do this every day; somebody else may need to make this repair).

With the spark plug out, I could see TDC through the hole. The starter and cowling over the flywheel had been removed previously. I could easily get the new pulley in place, the pin pushed up from the bottom, and the belt in place, cogged into the pulley.

But, are the alignment marks in the proper position? After a couple of tries, I had the alignment marks straight across from one another, just passing the view from the engine case. But, then I read the page from the manual again. It talked about compression stroke, and exhaust valve opening. "... if this is the case, then take off the starter ...." This was not very clear, not distinct as to "do this, and not this." But, I felt that I had used the wrong TDC. The crankshaft turns two revolutions for every one of the timing pulley. Four cycles: compression, power, exhaust, intake. So, the TDC will happen at the end of the compression stroke, and at the end of the exhaust stroke (hope I've explained that right).

Thinking I was wrong, I pulled it apart and started over. I got the alignment marks in the proper position for TDC, the second one.

Now, to replace the cover. The old one was sealed with a thick mastic that had been squeezed out, inside and outside. I tried to clean it off -- some stuck to the cover, others stuck to the engine case.

The only think I had to try to make a seal was Permatex. I smoothed some on the surface of the cover, and bolted into position. I replaced the fuel tank, and recoil starter. I put oil in the crankcase, and a little gas in the tank.

I pulled it off the table, and pulled the cord. On second pull, it started! Ah, ha, ... this is promising! I only let it run for a couple of seconds before shutting down. I didn't want to run the pump while dry.

After hooking up water, and the wand hose, I fired, and it started on first pull. It sounded good, and drove the new pump well. I shut it down after a couple of minutes.

My worst fear in now realized. Something is dripping from the bottom edge of the cover. I thought that perhaps some of the Permatex had gotten hot, and was just oozing out. On closer inspection, not the case, ... oil!

I refired, and ran for several minutes, cleaning off one of my mowers. I watched closely, and nothing was dripping.

After I shut down, more dripping. So, the pattern seems to be dripping on STOP, but OK during RUN. Doesn't matter, really. I have a problem.

My question to all you wise mechanics, what kind of material do I need to seal this cover? Obviously, there is no gasket available here. The pressures aren't high. Any suggestions would be appreciated.

Here are some pics. Sorry about the lack of continuity, and the one fuzzy one (having camera troubles this week). More on the next post.

05-16-2010, 09:31 PM
A couple more ...

First pic -- the key page out of the engine repair manual. Only the small piece at the bottom was applicable, as well as the diagram. But, that was enough to help!

The bag with the parts,

12310-Z0J-000 timing pulley
14320-ZL8-010 cover

05-17-2010, 11:01 AM
Bump, ... looking for an answer to the mastic question.

05-23-2010, 08:15 PM
Wow, ... this project is really getting frustrating!

Having no response to my question about a sealant, I stopped at the NAPA store. They told me to just use a silicone sealant. I went to the hardware store, but was not settled on what I found.

The tubes of silicone sealant were not specific on use on higher temperature applications. I was unsure about a typical silicone sealant in the kind of engine temperatures for an air cooled engine.

After browsing further, I found a Permatex product, one that seems to be intended for pliable, high temperature applications. The list of applications included valve cover gaskets. This seemed like a perfect fit.

I brought it home, took off the cover, cleaned the surfaces well, made the application as per instructions. I bolted up, but left it set for about 24 hours, not sure if it needed "cure" time."

See accompanying picture.

Today, I pulled it out, and fired the engine. The pressure washer really works well -- engine ran perfectly, and the new pump was more powerful than others I have used. I ran it for 15 minutes, washing down a couple of pieces of my equipment. Checking the underside of the cover frequently, I found no leaks.

Yea!!! ... got this project off my list. Or, so I thought.

When powering down, oil started to leak from the cover on one corner. It was a drip every 10 seconds, or thereabouts. By this time, the engine was fully hot at running temperatures.

This was the previous patter -- no leak when running, but leaking only when powering down.

Grrrrrrrrrr.... not a happy camper.

Not sure of what would happen to the gasket material after it cooled, I immediately pulled off the cover to clean the surfaces. The material has pretty much turn to liquid. It was getting to a goo stage quickly as it cooled. I cleaned off the surfaces on the engine, and it came off pretty well. When I got to the cover, the temperature of the part was nearly ambient. And, this stuff did not want to come off. It was difficult -- finally used a powered wire wheel to clean it off. I'm sure glad I did not wait for a couple of days to remove the cover, and THEN try to clean the surfaces.

Of course, my question: Why didn't this work? I'm doubting I will have a very good answer.

The NAPA folks told me they have sheet cork. That will be my next step -- cut a cork sheet to fit the cover. If a cork gasket does not work, then I'm at a total loss.

Here are few more pics -- the surfaces to be mated, and the package of the material that I used.

05-23-2010, 09:17 PM
There is a product that we used to use on motorcycles called Yamabond, by Yamaha. If you have a dealer in town, stop by and ask them about it.

05-23-2010, 09:24 PM
I did not realize that there were a few variations of the Yamabond. Apparently there is Yamabond 4, 5 and 6b. Here is a link to the Yamabond 4:


And here is a link to the Yamabond 5:


I am not sure which is right for your application. I think a little googling will answer your question though.

05-24-2010, 10:19 PM
Sorry for missing your question Roger, I use this when installing steel parts to machined aluminum; http://www.autozone.com/autozone/catalog/accessories/accProductDetails.jsp?counter=9&categoryDisplayName=&fromString=&itemIdentifier=526939_0_0_&productId=526939&sortType=&parentId=1309-10&filterByKeyWord=&categoryNValue=&navValue=100152&fromWhere=&itemId=152-10&displayName=3+oz.+(85+g.)+tube+High-Temp+red+RTV+silicone+gasket&store=288&skuDisplayName=3+oz.+(85+g.)+tube+High-Temp+red+RTV+silicone+gasket&brandName=Permatex

05-25-2010, 08:25 AM
Restrorob ... thanks for the tip. The words about the application sound right.

Does this product require a 24 hour curing period? Should the material be applied, the cover bolted up lightly, than tighten the bolts firmly at a later time (e.g. 12 hours)? Or, can it be applied, cover tightly bolted, and engine temperatures applied right away?