Discussion in 'General Truck Info' started by DYNOBOB, Feb 8, 2011.
Glad it all worked out for you..good job
So... They are expensive. What part of TN this time?
Norris/Coal Creek Rec Area again. You ever been there?
No i haven't. I heard its beautiful out there though. parents looked at some property on the lake there but down here you don't always get year round water. Im usually running around the cookville area. Got approx 5000 acres to run around on in white county up on bon air mountain.
UPDATE: ONE YEAR LATER...
The little Suzuki has quit running again. Picked it up Fri and checked the compression. Now at 64,120,175psi. All were near 200psi after the repairs last year. Haven't checked the valves yet but I suspect the intakes are tight again. It seems like it should run w/ 120 and 175 compression though...
Does anyone have thoughts on where to source a quality reman or used head? I've called Jacobsen/Cushman but they only sell the head in individual parts.
Sorry to hear that Bob, best of luck!
Checked the valves and can't get a .002 under any of the intakes. Obviously there's some bad juju going on with the intake valves and the head is coming off this time. I'm open to ideas though. I already have the thinnest shim they make in the intakes. It seems either the valves are stretching or the seats are moving up in the head. I've never heard of this happening across the board on all intake valves at the same time...
i'm going with the seats are receding into the head. (common on yamaha FZR600's back in the 90's for example)
take head to a shop and have the shop tip the valves when they do the valve job to get you back to normal shim sizes and set the head up on the bench...
at least you get steady work out of it.....
Just pulled the head. It appears the missing intake valve clearance is due to erosion on the back side of the valve. Luckily the seats look OK. Going to order six new valves/seals and timing chain/tensioner/rubbing blocks. The timing chain is loose enough you can see where it is rubbing the bottom side of the valve cover. My theory on the intake valves is they wore through their hardened surface 18-24 months ago and lost clearance. The thinner shims got the clearance back but it didn't last long due to no hardness remaining. You can see how much deeper in the head the intake valves are than the exhaust...
I haven't commented on your build repair at all cu'z, it didn't make sense to me. The problem didn't make sense and the solution, smaller shims, didn't make any sense at all...for a current condition fix OK, but valve clearance doesn't "walk" like this. If anything, the cams should be taking the wear but..."There is nothing as deceptive as obvious fact".
Having worked with hardened materials I can tell you that you could not have worn through a "hardened surface". Component hardening can be controlled laterally, tip to tip, or in this case, valve to stem, but not through depth. It is possible to "burn" the valves, but you'd be talking about almost immediate failure.
I think what you have discovered here is a bad batch of valves. Went through the factory during a process failure, power outage..who knows...
You got it locked down now. The only comment that I really had to pass along was that, like with any cancer, I would assume that a lot of that head is contaminated, and start "cutting". I think that you mentioned previous that the exhaust valves are already out-of-tolerance...If it was me, I would not leave those in there. I'd do all 12 valves and guides and go back to the original shim size. You don't want to have to operate twice.
Take it as you will. I think that you are doing a great job on this fix, and the patient is now off life support.
Thanks for your thoughts. It doesn't make sense. I've bounced this off several buddies who have a lot of experience w/ go-fast sport bikes motors and it's a head scratcher to them as well.
I agree that it could be a bad batch of valves but if so why would they last 45,000 km before they lost their clearance the first time...and then loose almost .010 in one year. I don't know.
We knew we were gambling last year by just re-shimming. The owners didn't want to get any deeper in at that time though.
The exhausts were not bad last year (with 45K km) and have stayed in spec since last year. I'm giving them the option to replace all while we're in there.
Think of it this way,
The valves got half the hardening of spec. From day one, maximum wear rate. As the gap opens, wear rate decreases to an almost static level. At 10thou...there's no more wear going on at the contact point. Giving you 60ish per jug...Will start in the dead of winter but, becomes a "lemon" and gets passed down the line...
You come along and shim it down, full pressure, full contact, and it starts all over again...Now you've got 64/120/175... it'll run, just not well, and probably won't start again once warm, but being a "lemon", if someone else owned this, they probably just keep driving it around "as is" and wear it back down to 60ish...
Kind'a makes sense but, I'd still have some follow-up future appointments booked for your patient.
The odd thing is it would not start even with 64/120/175. It did sound funny when it was cranking which leads me to believe the timing chain may had jumped. However, even if the timing jumped due to warn components, you're not going this deep and not figure out why the valves are tight again.
more to come...
I noticed this wasn't mentioned but is it possible there could be some valve seat recession?
Hi DYNOBOB. Sorry to hear of all your engine trouble. The engine condition you are experiencing is actually a very common issue we see at our shop. The previous owner was obviously not big on routine maintenance as evidenced by the excessive oil varnish on the head and the component wear you are seeing (good pictures by the way). Lack of oil changes and the use of low quality oil will accelerate wear at the cam chain links and sprockets. The "slack" at each link "stacks up" increasing chain lenght putting the valve train out of time. Further compounding the problem is wear on the sprockets where the links contact resulting in a decrease in sprocket diameter and resulting in the tight/loose chain effect due to the chain climbing the sprocket teeth. I strongly recommend replacement of all cam chain sprockets when you replace the chain to prevent damage to the new chain and ensure accurate valve trian timing and operation. You also mentioned that the engine was subjected to extreme dust conditions and that the air filter was in very poor condition. This will cause the engine to draw in air from anywhere it can in order to breathe bringing dust with it. Dust acts like lapping compound and will rapidly wear a groove on the valve face where it contacts the valve seat as the valve face is made of a softer material than the seat. The result is the valve receeding deeper into the valve pocket with the stem conacting the actuator and eventually losing it's seal at the valve seat. The problem is usually more evident on the intake valve as it sees the largest amount of dust. The valve adjustment did the trick until the contaminants at the valve face and seat wore off resulting in the same engine condition. The leak on #1 cylinder as indicated by the low compression reading will cause compression to leak back into the intake manifold creating positive instead of negative pressure (or vacuum) and make the engine very difficult to start as the fuel/air wants to go the other way. Your compression was good after the initial valve adjustment so your cylinder seal should be good. If you have a machine shop install new valves, guides and stem seals and you replace the above mentioned valve timing components and as long as the oil control rings aren't hooped from the lack of oil changes you should have a good engine again. Hope this is some help to you. Good luck with your new project.
UPDATE: I ordered one new valve to see how it looked in the head before ordering $700 worth of parts. We lapped it in and the seat contacts the valve face in the middle of the machined surface so that's good. I ordered 5 more valves, seals, chain, rubbing blocks, tensioner, and head gasket. Order just came but 3 valves are on back order until June 6th. So I'm at a standstill for now. We looked closely at the exhausts and left them alone since they show no sign of problems.
Thanks for the comments everybody.
wow...the valves were worn....can ethanol do that maybe ?
No Ethanol cant do that but dirt can, we have seen this at our shop as well on the Suzuki's. We believe its the result of dirt being sucked into the motor, we have no proof of this its just our opinion but that seems to be the common denominator when we see a late model suzuki with a compression issue that dont smoke. I have two heads for the K6A motor here at my shop for just this reason, had I seen this thread sooner I may have been able to help but it seems you have it figured out none the less.
I have a couple theories.
I can buy the dirt idea. Eight trucks were brought to the US in '06-'07 by a Japanese firm doing the site development for a new Honda Civic plant. The trucks were three years old when brought over. I've seen three of the trucks (mine is one) and they were all very, very dusty (but did have filters). The valves spin constantly when operating so any dirt acted as grinding compound. However this truck got a new air filter when I worked on it last year and still lost valve clearance again.
The other thing I'm seeing w/ both '03 Suzukis I've worked on is rust coming from the gas tank. I washed orange rust out of both trucks fuel rails and injectors (this truck not as bad as the other one I worked on). So maybe that could be the lapping compound. If you have one of these late model Carrys I'd recommend adding a very good fuel filter. My Hijet shows zero sign of rust in the tank.
My last theory is they got a batch of soft intake valves.
Separate names with a comma.