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Hello.

I have an 18.5 Briggs and Stratton Intek motor that gets stuck on compression when the starter turns.

I have ruled out valve clearances or cam issues (took it out for inspection).
My next step is to put it back in and clean up all the cable connections.

If I still can't get the motor to turn over through at least one cycle, is there a way to evaluate the starter?

I am attempting to start the motor with a truck battery and jump packs. The mower battery is bad.

Guess I will pull the starter and at least clean it up before trying again.

You have a good 12V battery with jumper cables and this does not turn ? Just make sure connection are good.

Are you able to turn the motor by hand ? If you position it just after compression, starter stops on next compression cycle ?

backporch said:

Hello.

I have an 18.5 Briggs and Stratton Intek motor that gets stuck on compression when the starter turns.

I have ruled out valve clearances or cam issues (took it out for inspection).
My next step is to put it back in and clean up all the cable connections.

If I still can't get the motor to turn over through at least one cycle, is there a way to evaluate the starter?

I am attempting to start the motor with a truck battery and jump packs. The mower battery is bad.

Click to expand...

No offense intended but I have seen numerous incidents where people think they adjusted valves correctly but were using the wrong method. Sounds like valve adjustment OR compression release to me. Yes, I see you say you have eliminated both. IF a starter is held engaged for too long an interval, the armature wind will over heat, loose resistance and thus torque. You can tell by the looks of the winding and smell. Reddish wire will look black and smell burnt. Do not hold starter engaged for longer than 5 seconds followed by at least 10 second rest period.

I had a similar problem come up all at once. Turned out the positive battery cable terminal was nearly broken off and not carrying enough amperage.

I can send you a Service Manual If you don't have one and would like it. Address below, put in proper format and remind me engine model number and what you want.

Walt Conner
wconner5 at frontier dot com

Sounds like your auto decompression lever came off your cam or valves need adjusting.

I took the engine pan off and the cam has the decompression lever in good shape. Its all back together now.

I was pretty careful setting the valve clearances. It is actually really easy compared to what I remember with my old VW air cooled engines. .003 on intake and .005 on exhaust. I set them at just beyond TDC on the compression stroke.

I can turn the engine by hand.

I also took the starter out and apart. Everything looked pretty reasonable. The pinion gear on top was messy because there was a mouse nest on top of the motor. I have that cleaned up and moving freely. The internals of the starter look good, no broken magnets, the brushes are in good shape and no signs of burning. Copper on commutator is nice and clean and shiny.

Going to fill the motor with oil and give it another try tomorrow.

I contacted the previous owner. He didn't realize that the fuse was blown so he started the motor by jumping the post on the starter from a car battery and jumper cables. If I can't get the starter to get past TDC I am going to give that a try.

Same situation with cleaned up starter.

Motor turns until it hits compression and stops. Tried jumpering at the battery terminals and also went right to the starter lug.

Looks like the intake stops moving about 45 degrees before TDC. I can manually turn the motor. If I manually turn it to TDC it also can't get through the power stroke.. may be pulling a vacuum there.

backporch said:

Same situation with cleaned up starter.

Motor turns until it hits compression and stops. Tried jumpering at the battery terminals and also went right to the starter lug.

Looks like the intake stops moving about 45 degrees before TDC. I can manually turn the motor. If I manually turn it to TDC it also can't get through the power stroke.. may be pulling a vacuum there.

Click to expand...

When you took it apart, are you sure you got the timing marks lined up?

When i put it all back together, I kind of regret not taking a picture of it assembled. I believe I got it right...the marks were pretty clear on both gears.

I was at Lowes today and I turned one of the display tractor motors by hand. The resistance of that motor to turning felt very similar if not harder than mine.

I ordered a starter last night from Amazon. Hopefully I won't get a bum part and the new part will fix my current problem.

Timing marks should match up, on the crankshaft you have a paint mark or dimple on the gear, and on the cam the same way.


the mark on the crankgear goes into the notch with the dimple on the cam gear.

the new starter didn't help. Sad to say.

With the spark plug out it spins like crazy.

I can watch the intake and exhaust valves while I turn the engine manually. I still really am not sure if the cam bump is working as it should.

I watch the intake valve doesn't appear to close until about 45 degrees before TDC. Right about when the starter stops. I don't see a pronounced bump ( closed intake open and close again). It just appears that the intake stays open a lot longer thanks to the ACR on the cam.

ACR working, clearances correct, but no strong crank

I am going to make this my last post for a while.... sorry for making this thread so long.

The ACR really seems to be working correctly. I can hear the pressure release through the open intake/carb. However the motor still gets "stuck" at 45 degrees before TDC on the compression stroke. That's just about where the ACR closes the intake valve.

My new starter is a lot like the old one. I even jumpered the starter post from my truck battery and it gets stuck.

With the spark plug out the motor spins quickly with no unusual noises.

The valve clearances are set correctly and the ACR is working, but I don't know where to go next. Could I have replaced a weak starter with a new starter with issues?

Did you remove all of the carbon buildup from both combustion chambers?

Re: Intek won't turn over ( PTO??)

The mower cranked really well the other day. Like all of a sudden something started working.

I got compression readings around 100psi. Crank was strong and fast. Purchased a new battery, gassed it up and after a little cranking it fired up and ran.

Next day I wanted to see if the transmission worked. Fired it up and put in gear, released brake and it stalled. Same thing happened again. Pushed it outside, started it up and engaged the PTO switch... stalled. I think it would only run with the brake on. Even in neutral it stalled when I released the brake. I was sure it was something to do with the belt being stuck... At some point there was a good amount of smoke. Wasnt oil burning off the exhaust.

Maybe now this makes some sense. Was the PTO resisting the engine cranking. Is my PTO gone? I don't really know how it works, but my next task will be to take it out and break it down. Not sure if they can be evaluated and rebuilt. New units are not cheap and I am not going to throw money at this mower until I at least make sure the transmission works.

Any thoughts about the PTO being the culprit? Can they be rebuilt?

Sounds like you have a bad/misaligned safety switch, probably at the seat. But the smoke thing needs to be figured out too.

I did disconnect the seat sensor. Thought I made the mower think I was in the seat all the time. Must have gotten that backwards.

Assuming my disconnecting the seat harness made it look like I was NOT sitting in the seat, is it possible to start the engine, but not move when not sitting? I thought even starting would be disabled.

I would love to see a writeup on how the PTO is supposed to work. Maybe I can find that somewhere

Well it would be nice to know WHAT Intek engine we are talking about, model number. However, locate the "Kill" wire running to the engine and disconnect it. Where depends on what Intek. IF the engine keeps running now you know it is a safety switch. Smoke indicates deck bearing or drive system is locked up, maybe something jammed between belt and pulley, bearing froze in deck. Understand this happens with deck in disengaged position so check drive system for frozen idler, stick in pulley as said before.

Walt Conner

Mower wiring 101
Cranking Circuit
Power usually goes from the hot side of the starter solenoid .
1) through a fuse
2) the the B ( = battery) terminal on the ignition switch ( tiny numbers under the switch )
3) to S (= Start) terminal on the switch
4) the the PTO switch or PTO safety switch on manual PTO's
5) to the brake safety switch
6) to the trigger wire on the solenoid.
This is a daisy chain so a break anywhere = no cranking
If the solenoid has only 1 small wire then the ground is via the case which will benefit from a clean where it contacts the body of the mower to get a good contact.

The ignition control can either be on the key switch
M + G = off
or on the throttle plate.
follow the thin wire from the coil
This is a ground wire.
Ground = off
Open circuit = on

Except on some ZTR's the seat switch is not in the cranking circuit.

Your problem is the ACR.
Your inlet valve should open just before TDC exhaust stroke then remain open all the way to BDC then close as the piston starts to rise.
Just before TDC the inlet should open a very small amount then close again .
Put your finger on the rocker or pushrod, you should feel them go tight then slack again as the ACR kicks in and drops out.

This is SOP for checking the cranking circuit
Before you start, pull the spark plug & try to rotate the engine by hand.
No use checking the electrics if you have a hydraulic lock, seized engine or jambed belt overloading the stater motor.
Assuming the engine turns freely.

I like to start from the starter motor and go backwards .
Do the following 5 tests, regardless of the results from an or all of them as there can be more than one problem and you want to isolate where the problem lies.
Elimination of individual parts is important so you know by the end, the battery, solenoid & heavy power circuits are all in good order.

1) try to jump the starter motor directly from your car or truck.
+ on the starter first then - to a good ground near the starter ( drain plug of lift hook are good )
Starter turns = starter good

2) do the same directly from the mowers battery
Starter turns = mower battery good
No turn = duff battery, recharge it & try again.

3) check for voltage ( + 12V ) at the solenoid trigger wire with the key in start position
3a) same with ground trigger wire ( 4 wire solenoid ) or body of solenoid ( 3 wire solenoid)
( I like to test V from the battery hot terminal to ground terminal rather than ohms as they give funny readings )

4) leave ground jumper in place ( from step 2 ) & try key start.
Starter turns = power connection good but ground connection suspect ( most common )
Confirm it by trying again, extra ground removed

5) Remove the trigger ( thin ) wire / wires from the solenoid.
Ground one on a 4 wire solenoid & bridge from the hot terminal to the other.
Starter cranks = solenoid good.
Solenoid is not polarity sensitive, BUT THE WIRING IS so make sure you remove the thin control wires.
Note a thinner wire on the hot terminal is not a control wire. It is the main power feed to the mower.


From here on things become very mower dependant as starting circuits are getting changed all the time.
Basically the power goes in a loop from the hot side of the solenoid ( saves wire, no other reason ) through the fuse to the B terminal on the key switch then to the PTO switch then to the parking brake switch then to the solenoid trigger switch , easy peasy after you grow the 3rd arm. Use a test lamp and follow the power.
However a lot of mowers with a 4 pole solenoid, run a secondary ground control circuit to the ground solenoid wire through the lap bars.
Then to stop this interfearing with the normal safety function of the ground kill, it goes to a relay with the ground as the switched connection.
These are a PIA as the + control wire to the relay comes from the power loop above and the ground side of the control comes via the normal cut out functions of the lap bars.
Be very careful because if you have a system like this and accidentally send 12V down the ground loop you can fry the magnetos on some circuits.nd from the grounding bolt to one of the starter mounting bolts & paint over both with liquid electrical tape.

The mower is a DYT4000 Craftsman. Motor is 18.5 hp Intek Briggs and Stratton. 31P7770384E1.

I really think the PTO was the root cause of my issues. it was pretty hard to rotate until I backed off the adjustment nuts a little. That may have been my starting problem and I believe it is also the cause of the smoke. I don't think I burned a belt.

If the clutch engages, but the pulley that it activates is not able to spin, I imagine the clutch would wear. Still don't follow exactly how it works and if it is repairable or if any maintenance/troubleshooting can be done

I put 12v across the two wires and the electromagnet did click, so the most basics of the clutch is working. PTO is part number 180505

No, don't mess up a good clutch. The clearances of the clutch, set them @ .015 with a feeler gauge.

Thanks fish.

I won't try to take the PTO apart. I will set the clearances with the adjustment screws and put it back together. may not get a chance to test it until I am back next week.

I will also make sure the seat harness connector is connected when I go out for the next test ride.

mower seems to be working well now.

The smoke that I thought might be the PTO was oil burning off the muffler.

I did adjust the PTO and reinstall. I tested prior to install and it activated and did not scrape at all on the stationary part of the PTO.

I don't really know what the root cause of the mower not cranking was. It just seemed to all of a sudden start working better. If I had more faith in the mower I may have been able to avoid all of the troubleshooting by just buying and installing a new battery.

backporch said:

mower seems to be working well now.

The smoke that I thought might be the PTO was oil burning off the muffler.

I did adjust the PTO and reinstall. I tested prior to install and it activated and did not scrape at all on the stationary part of the PTO.

I don't really know what the root cause of the mower not cranking was. It just seemed to all of a sudden start working better. If I had more faith in the mower I may have been able to avoid all of the troubleshooting by just buying and installing a new battery.

Click to expand...

Thought I would give an update on this. My mower still has cranking issues but has served me well since this post
The battery needs to be charged. Before starting but once I do that I typically get a full rotation and maybe another full rotation each time getting hung up on the compression. The next turn might get it to start cranking several rotations and then fire up and run. This is at 70 degrees or better. I don’t expect it will ever start in cooler weather

Looking back at this I realize I have gone 5 seasons on that Walmart battery. Probably well overdue for a refresh