OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk Gxv 120: oil in valve housing?

Hi guys, lately i have noticed that my old hr214 has been puffing a bit of the white/blueish stuff and i want to have a look at whats going on (getting the new piston rings ready i guess). Also, from my reading on here it seems that the whitish stuff could be due to valve clearance not set correctly or valve seats stuffed. Anyhow, i opened up the ohv cam cover to find a small pool of oil at the bottom, is this normal or are the seats/valves stuffed as well?

thanks!

Johno, I suggest you do the oil-in-the-sparkplug-hole trick, and check the tappet clearances, to check whether your problem is mainly rings or mainly valves. There may be some involvement of both.

Your engine is pushrod OHV, and it needs some oil in the rocker compartment to lubricate the valve gear. However it probably has worn-out piston rings, and that does not give it a fair chance at keeping its interior clean. The blow-by past the piston rings is likely to exceed the capacity of the crankcase ventilation system, resulting in excess oil passing through the breather system into the intake port and getting past the valve stems into the rocker compartment. In other words it may or may not have worn valve guides, but it probably has other reasons to have oil in all the wrong places, so you should not judge just by the presence of oil. If you find you need to replace the rings, you can check the valve stem clearance in the guides at the same time. There is a Honda workshop manual for the HR194 & 214 in the parts and manuals section of this site.

thanks grumpy, i do suspect a bit of both (valves and rings) as this is an old mower that was previously a contractors (hr214).

I have done the oil in sparkplug hole trick and have noticed an increase in compression so i guess it does need new rings.

(i have also dismantled the mower and just moving the head of the piston around i feel 1-2mm or so of freeplay in the bore which i guess is no good, i know its not supposed to be a perfect fit but when i can move the piston around and see oil coming out of the bottom between the piston and the bore, it cant be a good thing).

also, the bore seems in perfect condition, do i really need to hone it before reinstalling new rings (it would involve buying a honing tool for me and i cant see myself honing to many bores to make it worth it).

Johno, replacing the rings will not improve the piston slap problem. The piston skirt (i.e. just above the bottom edge of the piston) should have a maximum permissible clearance of 0.12 mm (0.005") to the cylinder wall, which is a lot less than 1-2 mm. Normally the cylinder bore would be worn in a tapered fashion (maximum bore size about 10 mm below the top face of the cylinder where the cylinder head mounts), so you need to measure the skirt clearance with the piston at the top of the stroke.

Unless you are wrong about that 1-2 mm, it sounds as if you are in desperate need of a rebore, an oversized piston, and oversized rings to suit. Bearing in mind the price of Honda spare parts, I think the contractor may have effectively extracted the last economically available life from that engine.

Because you are not a contractor, you may decide you are prepared to run the engine with mechanical standards that are not acceptable to Honda, or to a contractor (in other words, reduce the smoke rather than cure it). Before you decide about that, while the cylinder head is off, measure the bore at right angles to the axis of the crankshaft, 10 mm below the top of the cylinder. Compare that dimension with the service limit of 60.165 mm (it measured 60 mm when it was new). If you are very far outside that service limit, this will not be a practical project - but how far is "very far" is difficult to say without experience in that particular engine type.

ok, well maybe i exaggerated with the 1-2mm :P

i will have a look later on as to what the actual bore dimensions are and go from there. I dont want to give up this mower... its my favourite

It should be a nice mower, Johno, provided it isn't too far gone. If the dimensions are OK and you go ahead with the re-ringing, we can talk about how you can break the glaze in the bore without going to the expense of buying a hone. Most likely I won't be the only member here with a pet method that has worked previously.

Note for B&S overhaulers: Briggs and Stratton recommend that you do not break the glaze of an aluminium bore, when replacing the rings:

http://www.tpub.com/content/recoveryvehicles/TM-5-4240-501-14P/css/TM-5-4240-501-14P_250.htm

Bore has never been stroked! 600mm in dia guess the play just looked big to my eyes! So how can I deglase the bore?

Btw, this measurement was done with Vermeer calipers so it might not be 100% accurate.

Johno, it sounds as if you may have fallen into a trap. The piston rings do not reach the top of the bore, that is why I said you need to measure the bore at right angles to the crankshaft, 10 mm down the bore. By using vernier calipers, you have actually measured the top edge of the bore, which has never experienced any wear. This part has what is commonly called a "ridge" which is of standard diameter, and prevents the piston from being removed from the cylinder by pushing it upward, since the rings catch on the ridge. It is standard automotive practice to remove the ridge with a special tool at the beginning of engine overhaul processes.

You need to measure the bore in the place I said, preferably by using an inside micrometer, but failing that, by using inside calipers and transferring the dimension to your vernier calipers. I think you will find it is at least at the Honda service limit for diameter, but probably quite a bit larger than that.

i see the problem...

i will re-check the piston with inside calipers and then note the dimensions here.

i feel really stupid but what you stated makes perfect sense!

ok, the reading i have here is 60.18

what do you think? is it too far gone?

If that bore measurement is accurate, and is at the maximum diameter location (remember, at right angles to the crankshaft, because the piston is pushed sideways by the tilt of the connecting rod as it begins to move down the bore, so this is the maximum wear-point) I would accept it as OK to re-ring the engine with standard rings. When you get the piston out you will be able to check the ring-grooves for wear. If they are OK also, you can re-use the piston.

Because the bore has some wear, you need to deglaze it with minimum metal removal so it doesn't become even larger. The idea of deglazing is to end up with a cross-hatched pattern of honing marks around the bore, at about 30 degree angle to the bore, symmetrical in both directions. You can do this with some fine emery cloth, or even wet-and-dry, kept oiled while you rotate it in the bore with your fingers. However a better way is to make a simple lap. This is a round piece of wood of a couple of mm less than bore diameter, with a piece of steel rod axially through its center. You saw a slot in the cylinder, longitudinally, and angled forward of radially, so you can tuck the end of the emery cloth into the slot and wrap it around the cylinder. To break the glaze you slide the wrapped cylinder into the bore and mount the end of the steel rod in an ordinary electric drill (either hand type or bench type, so long as it can be reversed in rotation, and can be run slowly). You then run the drill slowly while rapidly moving the cylinder up and down the bore. Keep the emery cloth wet with oil. After about 20 seconds or so, stop, take the lap out of the bore, wipe it clean with a cloth, and look for the lapping pattern of rub marks in the bore. When you have largely disrupted the glaze without removing a noticeable amount of metal, take the wooden cylinder off the steel rod, put it on the opposite way around, reverse the drill's direction of rotation, and repeat the process exactly. When you inspect the bore you should then see the required even, cross-hatched pattern of lap marks.

Remember, you must keep abrasives from entering the crankcase, so wrap everything down there in clean rags before you start. The emery cloth should be about 200 grit size, but opinions differ on this. (I once reclaimed a Lister cylinder by using coarse floor-sanding paper until I got to the bottom of the pits, then shifted to finer cloth to produce the honing pattern).

bore was measured horizontally , approx 10 mm into the bore with inside calipers,repeated 2 more times for precision and that was the value obtained on all times.


thank you for all your advice grumpy and for making the effort, writing posts as long as the ones you have written take time and effort and i do appreciate it.

i will keep this thread going and inform you of how it all went (getting piston rings tomorrow hopefully.. they had to be ordered in.. seems like the 120 are running dry and honda just focus on the 160s now yeah?)

Johno, please keep the thread going rather than tell us after you've made an attempt at things we haven't discussed. There are some complications regarding valve lapping, checking the valve guides, and cleaning/measuring the piston, that could work out badly if you rely on guesswork. Meanwhile, though, some pictures of your piston/rings when you remove it, measurement of the ring gap for your old top compression ring, and a picture of your bore after you de-glaze it, would be useful for the archive.

will take as many photos as i can as it comes along!

ok, its gotten a bit dark so i will continue the work tomorrow.

1 problem, i have snapped the compression ring before taking a photo (measured and was no good so i snapped it so i can use it to clean with it). the gap was <0.015 though.

the piston size is 59.95mm so i guess its within hondas service limits as well.

i have never really lapped valves (i honestly was not thinking of doing it, just changing rings and off i go) but i guess if its better i do it now then i might as well learn on this old beast).

It is essential to lap the valves - they may have been leaking, and most likely they have not been lapped in the time it took to wear out the rings, so it is more than due. The process is usually simple, but that depends on the condition the seats are in at present. The first thing you need to do, though, is check how well the valve stems fit in the guides. If they are rattly-loose, you can't lap the valves successfully until they are corrected. I suggest you follow this process. First, measure the valve stem diameters, in the wear area (i.e. where they slide through the guides). Nominal diameter is 0.217", minimum is 0.209" for inlet, 0.208" for exhaust. Second, try to measure the amount of slack between stem and guide. I would do this with a dial gauge against the valve head, pushing it from one extreme to the other and noting the movement in between. I think you will need to set up a stationary object close to the valve head, then use feeler gauges. The nominal valve guide internal diameter is 0.217", and the maximum is 0.222". This means the maximum valve head movement (worn out valve stem in worn out guide) is 0.011" inlet, 0.012" exhaust. If you have more movement than that, you can calculate what the movement would be with new valves in the old guides. If it is still excessive, you need to either ream out the guides and fit new valves with oversize stems, or renew the valve guides.

Please let us know how the valves and guides measure up. There is no point in lapping valves that you are going to have to replace.

ok, have checked the valve stems and have checked the width of seats, have also checked valve free play but it is so minimal that i could not get the finest feeler guage into the gap for either one (finest feeler gauge i have is 0.015 or 0.04mm) obviously i could not measure the valve guide ID because i do not have the necessary equipment.

VALVE STEM OD IN: 5.425

VALVE STEM OD EX: 5.455

VALVE SEAT WIDTH IN: 1.2

VALVE SEAT WIDTH EX: 1.0

It seems that there's still enough meat in the valve seats to lap away. Should i go ahead and use the guides and valves that i have? (they seem within service limits).
Also, i have read a bit about valve lapping and it makes sense, basically using the valve as a guide to essentially grind away at the valve/seat so they marry well, yes?

PS: Sorry i have notcied ur talking inches, im talking mm, hope it does not bother you.

PS, anyone have any hints on how to remove excess carbon from the ex valve using some sort of solvent or something? (i woudnt want to start scratching away using a scraper etc in case i damage anything).