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Bill McCusker
Bill McCusker, Mechanic
Category: Small Engine
Satisfied Customers: 55
Experience:  Mechanic at Rhode Island Harvesting Co
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I have a power washer with a 175cc OHV motor that wont

Customer Question

I have a power washer with a 175cc OHV motor that wont start. I've changed the coil/armature spark plug the gas is new this season as I store this in the basement in the winter. This was running perfect a month ago last time it was started. I'm not get a blue spark as expected, getting a yellow/orange spark. Any thought on what I can do next would be great. Thank You John
Submitted: 12 months ago.
Category: Small Engine
Expert:  Curtis B. replied 12 months ago.

Welcome to JUST ANSWER small engines, let me try to help you !! I don't know it all, but maybe together we can get you a satisfactory answer!

Expert:  Curtis B. replied 12 months ago.

If you remove the kill wire from the on/off switch will engine start?

Customer: replied 12 months ago.
no
Expert:  Curtis B. replied 12 months ago.

Same if you remove the kill wire from the coil? Coil and magnet is all that makes the spark!

Customer: replied 12 months ago.
still wont start..I'm getting spark not a blue spark as expected but yellow/orange
Expert:  Curtis B. replied 12 months ago.

is this with new spark plug?

Customer: replied 12 months ago.
new plug
Expert:  Curtis B. replied 12 months ago.

Maybe spark is ok. If you out a teaspoon of fuel into the spark plug hole, re-install spark pug, will engine start?

Customer: replied 12 months ago.
no still wont start
Expert:  Curtis B. replied 12 months ago.

Have you removed the fuel bowl and checked for water or debris in the fuel bowl? Common problem on pressure washers!

Customer: replied 12 months ago.
all clean
Expert:  Curtis B. replied 12 months ago.

Have you checked compression? Hold finger with rag over spark plug hole, and see if it has enough compression to move your finger.

Expert:  Curtis B. replied 12 months ago.

How are you checking for spark? Plug grounded to the metal of the engine?

Customer: replied 12 months ago.
compression is good
Customer: replied 12 months ago.
I'm no expert but i"m pretty good with motors this one has me stumped
Expert:  Curtis B. replied 12 months ago.

Spark seems weak, but coil and plug and kill wire has been checked or replaced. Will not fire with fuel in the spark plug hole. That only leaves the timing between the flywheel and the crankcase key.

Expert:  Curtis B. replied 12 months ago.

Or the valves are not moving!

Customer: replied 12 months ago.
check the timing that is good also appears valves are working properly
Expert:  Curtis B. replied 12 months ago.

OK< I will opt out. Sorry. maybe someone else will have seen this.

Expert:  JohnF2015 replied 12 months ago.

Hi, my name is***** will be assisting you.

I have read the prior conversation in regards ***** ***** issue and it sounds like you have covered just about everything that could be an issue however I have seen a large number of these engines especially mounted on power washers that have this issue and you will normally find the problem to be the crankshaft gear that actually turns the cam. The original crankshaft gear was made of a composite or plastic material which did not hold up well in power washer applications, it would strip the locator key that was molded as part of the gear and then would let the gear spin free on the crankshaft and no open and close the valves properly. If you watched the valves as you slowly turned the engine over it appears that everything was working okay but if you pull the rope quickly as if you are trying to start the engine you would find that the valves are not operating at all due to the crankshaft gear slipping on the crank. I had this happen to my own personal power washer as well, I had been using it everything was fine no problems, shut it off, went to use it again a couple days later and it would not start, this is exactly what I ended up finding wrong with my unit as well as a large number of others that I had come into the shop for repair.

In order to repair this you will have to take the engine off of the machine, remove the lower oil pan from the engine. Once you have done this you will have access to the crankshaft gear and you can then remove the old gear and replace it with a new gear. The new gear is cast rather than composite. Briggs part # 797521.

I hope that this information helps you.

Thank you it has been a pleasure to assist you.

Please take a moment to rate your experience.

Expert:  JohnF2015 replied 12 months ago.

Make certain that if you are doing this repair that when you reassemble the crankshaft gear that the timing marks on the crank gear and the camshaft gear are aligned prior to putting the lower oil pan back on, this is what actually times the engine.

Customer: replied 12 months ago.
valves are working as they should when I pull the starter rope.
Expert:  JohnF2015 replied 12 months ago.

When you pull the rope quickly as if you were trying to start the engine?

Customer: replied 12 months ago.
Expert:  JohnF2015 replied 12 months ago.

I have seen this happen on a large number of these engines.

Everything else looks good in basic checks but the engine will not start even when you spray carburetor cleaner or fuel into it.

Expert:  JohnF2015 replied 12 months ago.

The only other thing that would cause a no start in that case is a bad or weak ignition coil.

What is the ignition coil clearance set at between the coil and the magnet on the flywheel?

Customer: replied 12 months ago.
coil .010 of an inch spark plug .030
Customer: replied 12 months ago.
this is a new coil. took ohms reading 6.134k ohms
Expert:  JohnF2015 replied 12 months ago.

I don't have any other suggestions for you. It sounds like you have checked everything that could cause the problem.

Even though it is a new coil it could still be bad however.

I am still thinking that it is the crankshaft gear that is causing your issue because I have seen it happen a lot on this engine mounted on power washers.

I will opt out which will allow for one of the other experts here to add and comments if they have other suggestions.

Customer: replied 12 months ago.
thank you
Expert:  Bill McCusker replied 12 months ago.

Hello my name is ***** ***** of the things i would do if this came to my shop.. Check the valves to make sure they are in the right spec. I would also do a leak down test it may be that the valve isnt 100% close.. causing no room for compression to run.. if everything is ok..

Customer: replied 12 months ago.
ok i wouldn't have the equipment to do those test. However I do have good compression at the plug. Valves are clean and look good . I don't think valves are the problem.
Expert:  Bill McCusker replied 12 months ago.

You remove the head and looked at the face of the valves?

Customer: replied 12 months ago.
no i did not take the head off. this motor ran perfect when last started. in all my years working on small and large motors I have never seen a valve have problems in that short of span. I'm leaning to something electrical still. If I had compression issue then maybe the valve.
Expert:  Bill McCusker replied 12 months ago.

I have seen you have might have compression but if you do a leak down test you will see there is a valve not closing 100% so you might have to lap the valves.. All the timing is good?

Customer: replied 12 months ago.
timing is good this motor only has about 5 hours on it. Can't believe it would need to have valves done.
Expert:  Bill McCusker replied 12 months ago.

ok fair enough.. I didnt know it was new..

Expert:  Bill McCusker replied 12 months ago.

I will opt out cause if you are getting spark, fuel and compression.. all should start.. Good luck

Customer: replied 12 months ago.
thank you. I agree should start