QuestionQUESTION: Hi, I've scoured the postings and found many people with similar problems but only 1 or 2 with identical problems to mine. I have a Toro Timecutter 14-38Z (model 74301 serial 230004085) zero turn mower with a Briggs %26 Stratton 14HP OHV engine (model 280H07-0166-E1) and it only has about 120 hours of use from new, although it was stored for past years while I relocated to New Jersey (drained of gas)
After checking oil and fluids, putting in new battery, cleaning the air filter(s), and changing fuel filter and lines, the mower started right up.
After a couple of hours use, the engine started to strain under load. At first I noticed the hydrostatic drive was straining at full throttle. Upon engaging the blades, I could hear that they took a while to spin up. I had problems cutting the grass, and mower was choking on the grass. If I went up a slight incline, the whole mower started to vibrate/ shake.
I first took apart the carb , and cleaned thoroughly with carb cleaner and compressor. I also checked the hydro drive for obstructions, and sharpened the blades and greased the bearings and wheels to ensure it was as efficient a cutting machine as possible. The carb had no buildup and the solenoid was working fine. The plug was not fouled, and had a light coating of emissions, but dry of oil, and sparking strong.
If I disengaged the hydro and the blades, the engine seemed to idle fine, but the tappets were rattling, and the engine didn't increase rpm after about 2/3 of max. Instead, I heard a dull popping sound.
Last weekend, I adjusted the valves to within tolerance (0.004" intake and 0.006" for exhaust), and checked for a partially sheared key (key was fine). Valves had some slop, but not much, and engine always started easily. Still no improvement in power !
After taking the valve cover off again, and turning the flywheel by hand, I noticed that the exhaust valve has a good amount of travel, but the intake valve is hardly moving. I notice it has two movements. One almost undetectable straight after the exhaust stroke, and one again on the next stroke, but nothing like exhaust. I checked that the valve springs had good travel, and they both did, so nothing binding the valves.
I finally took the intake push rod out thinking it must be broken or bent, and it was perfect. I could roll it on the garage floor and it was perfectly straight.
After lifting off the head, and holding the intake push rod in by hand and turning the engine (quite tricky with oily hands!), I noticed very little movement on the push rod, maybe an 1/8".
I've heard of people saying that there was a heat treating issue on intake cam lobes on B%26S OHV engines thus leading to premature cam lobe wear. Could it be this or could the tappet valve at the bottom of the push rod (making contact with the cam lobe) have been worn/disintegrated?
If so, before I begin the larger task of lifting the engine out of the mower to access the crank case, is there another way of verifying I need a new cam shaft or the lesser tappet valve?
There's a lot of collateral to remove from the engine before I could lift it out, especially on a hydrostatic drive mower, but am willing to do this if I have to.
Apart from a bad camshaft, what else could cause this premature loss of power?
Finally, the zero turn is pulling slightly to the right, and not sure if that is related to lack of engine power (not giving enough to each differential) or another problem?
Your diagnosis on other posts has been very very helpful in getting this far, and I thought that the valve adjustment would have done it, but alas I'm having to turn to you experts to get a resolution. Getting this to a shop to repair would be crushing, especially since I've been unemployed for 9 months and fixing everything in my house (since time is what I have).
Please let me know. If I need to order parts, I'd rather do it today or tomorrow so I have a decent shot of getting this fixed before my next mowing. I ended up using the walk behind Honda and sharing this duty with my wife to cover the 0.80 acre lot and it was 90 degrees.
Thanks in advance and best regards
ANSWER: hi khurram
here is web site for parts breakdown
http://www.briggsandstratton.com/maint_repair/manual_and_more/docsearch.aspx?eng
i do believe that a camshaft lobe could be causing the problem the low lift of inlet valve is very suspect because you mentioned - rockers good , p / rods straight, valves adjusted
carb solenoid good , carb clean , clear , fuel @ carb and fuel pump working
engine acting as if not getting enough fuel @ higher revs - because inlet valve open duration too short ( from low lift )
do you remember if the valve clearance on inlet was very wide with very little opening movement
only thing left is either worn cam lobes or cam gear timming out / stripped teeth , but sound more like worn cam lobe
if you were to tighten down the inlet valve clearance( do this carefuly ) turn engine by hand until you have the inlet valve opening the same amoubt as exhaust - then worn camshaft would be indicated
the inlet valve does have a decompressor action just befor tdc compression stroke this is part of camshaft and only comes into play at cranking / starting speeds not at rev
be sure to check that inlet valve follower is not stuck and is free to move
be sure that inlet valve is not sticking / stuck in its guide
i am sure you have ruled out compression and spark , and fuel and timming
pull the engine and remove sump plate - check camshaft / lobes - teeth and gears
off the top of my head you will need
pto seal 791892
790400 camshaft set includes followers
697151 engine gasket set ( gives everything needed to rebuild )
valve movement and travel opening / closing is tied to cam shaft / lobes and push rods and rockers everything being equal and followers free and timming good , valves free in there guides can only be camshaft
have a look and keep me posted
cheers paul
check out web site
---------- FOLLOW-UP ----------
Worn Cam Lobe
QUESTION: Hi All, especially Paul
Thanks for the info on the parts to order. Incidentally, the valve clearance when I initially took the rocker cover off was about 0.010" on intake and 0.08" on exhaust. Enough to reliably start the engine. So after adjusting to 0.004 and 0.006, I thought I'd be golden, but alas, it didn't give any extra power.
Okay, here's the update. I managed to get the engine out of the bay today after first removing blade belts, hydro belts, PTO clutch assembly, carb, cables etc.
Taking off the sump cover/ crank case cover, I peered inside and could immediately see the exhaust cam lobe touching the cam follower. When I looked at the other cam lobe, it was almost circular ! Pulling the camshaft out and examining, I was floored ! There was hardly any indication that the cam was EVER an oval, as it looked round. I could see minimal burring on the edge, but other that that nothing. I had changed oil after my initial problems started happening 2 weekends ago, and the old oil looked dark, but it was almost a full 48 oz load, so it never got low. The new oil I drained before tearing the engine was golden, BUT there was graphite like sludge at the bottom of the crank case and crank cover. So my cam lobe must have been made of #2 pencil lead !
I've taken plenty of pictures if anyone ever wants to see a worn cam lobe, but can only attach one pictur to this thread. I may try putting them up on my MobileMe site and list the url for you guys.
Thanks for the prompt and accurate responses. You guys rock. I'll order parts tomorrow (or try my local lawn mower repair place to see if they carry), and assemble as soon as I get them. In the meantime, I'll clean the thing up while it's on my garage floor.
Secondly - The engine speed governor device isn't exactly obvious to put back - Any pointers? Torq settings on crank and head bolts? is 15 ft/lbs? Any particular order ?
The camshaft does have the dot stamped in it, but it wasn't obvious what it lined up with at TDC. I had out the engine at TDC before tearing down, and when I looked at the camshaft, the dot was at about 2 o'clock. Should it have lined up with something else?
I did dig out a manual from Toro's website that is more detailed than the mower's ! It says the units do not require fluid's at any interval but should be checked from time to time (oxy-moron) They have conveniently provided a 30 inch garden hose that stands up into the frame for expansion only (when the oil gets hot), but it is only possible to check the level by "removing the entire hydro assembly from the mower chassis ! You are right. Then if the oil is degraded, yes, turn it upside down. My feelings are that the right hydro may have leaked some of it's oil and be low, thus causing the mower to pull to the right. The reason is that the right hydro had some oil discharge under the grass cake. So while I have the engine and belts off, I will remove the hydro assembly and service with the Royal Purple Brand.
Answerhi khurram
glad to hear diagnosis was spot on !
i will gather info on cam timming and torque specs for case bolts and cylinder head bolts
etc and send them to you tommorrow
from memory dot on crank pinion gear should line up with dot or the 2 slash marks
on camshaft - to be sure i will let know tommorrow !
did you download a parts breakdown off web site
www.briggsandstratton.com/maint_repair/manual_and_more/docsearch.aspx?enginelookfor=280h07-0166-e1
this helps with parts relationship when reassembling
will send data / specs tommorrow
cheers paul
update here are specs you need -:
cyl head bolt torque 220 in/lb or 18.13 ft/lb
tighten to 110 in/lb ( 9.16ft/lb ) 1st then to 220 in/lb ( 18.13 ft/lb ) second
align crankshaft timming dot with camshaft timming dot . .
both dots must align
push rod guide / rocker stud torque 85 in/lb (7.08ft/lb)
fit lash caps to valve stem top if used and fit push rods and rockers etc
alloy rod is inlet / steel is exhaust
set piston to tdc compression stroke and then run piston 1/4 down the bore on power stroke
then set inlet to 0.003" and ex to 0.005"
make sure governor cup is in line with the governor shaft paddle
sump plate with new gasket bolt torque 200 in/lb ( 16 ft/lb)
fit new seal ( use protector so you dont knick lips of seal while stalling flush with cover )
new rocker cover gasket
v/cover bolts to 60 in/lb ( 5 ft/lb)
rc12yc plug, new oil and filter -
0.010 armature air gap
once engine assembled
adjust governor - : move the governor link rod and throttle plate to fully closed
then move it to fully open ( note the direction that the governorarm and shaft moved ) while being moved from full closed to full open ( this should be clockwise) hold the throttle plate at full open and loosen the governor shaft clamping nut and turn the governor shaft fuly clockwise and tighten nut ( note do not force governor shaft)
cheers keep me posted how she comes along
paul
here is web site for your timecutter 14-38 sz illustrated parts breakdown
http://www.partstree.com/parts/?lc=toro_consumer&mn=74301%2C+14-38Z+TimeCutter+Z
