Mobile Spark Plug Replacement & Engine Diagnostics Great Falls MT
Engine has spark but won't catch, or running rough? We run spark, compression, and valve clearance diagnostics at your home to pinpoint the issue.
About Our Spark Plug & Engine Diagnostics
An engine needs three things to run: fuel, spark, and compression. If your engine is misfiring, running rough, backfiring, or completely dead, Flying Wrench provides scientific on-site diagnostics. We carry digital spark testers, compression gauges, cylinder leak-down tools, and feeler gauges to check ignition systems, cylinder health, and overhead valve clearances. We replace fouled spark plugs with correctly gapped replacements, test ignition coils, and adjust valves, saving you from replacing an engine that just needs a simple adjustment.
Specialized Work We Handle:
- Digital Ignition Arc Diagnostics
- Cylinder Compression Gauging
- Overhead Valve OHV Feeler Adjusts
- Champion Spark Plug Swaps
- Ignition Armature Gap Settings
- Sheared Flywheel Key Repairs
Why Choose Flying Wrench for Spark Plug & Engine Diagnostics?
Precision Ignition Coil & Armature Air Gap Adjustments
We travel directly to your home, farm, or business to perform diagnostic and mechanical repairs on-site.
Compression & Cylinder Health Reports Provided
Certified mechanical technicians with full county licensure and WCB liability coverage.
Overhead Valve (OHV) Adjustments Done on Driveway
Clean, upfront diagnosis and written quote estimate options before a single bolt is turned.
Solve Misfires, Rough Running, and Hard Pulling Engines
Locally stationed out of Great Falls, MT, ensuring the fastest scheduling for your tools.
Request A Free Quote
Fill out the form below or call us for same-day mobile service.
SERVICE DEPLOYMENT WORKFLOW
What you can expect when you hire Flying Wrench for your spark plug & engine diagnostics needs.
Step 1: Ignition Spark Test
We use inline spark testers to verify if the ignition coil is producing a strong, consistent electrical arc.
Step 2: Compression & Leak-Down Test
We check the cylinder pressure to confirm the piston rings, head gasket, and valves are sealing properly.
Step 3: Valve Clearance Check
We pull the rocker cover and adjust the intake and exhaust valves to factory clearances using feeler gauges.
Step 4: Spark Plug Refresh
We inspect the old spark plug for oil or fuel fouling, gap a brand-new plug, and install it to torque specs.
Spark Plug & Engine Diagnostics Frequently Asked Questions
Common questions about our spark plug & engine diagnostics service in Great Falls, MT.
A black, wet spark plug indicates fuel fouling (the engine is getting too much gas or the spark is weak) or oil fouling (oil is bypassing worn piston rings into the combustion chamber). We will diagnose the underlying cause.
This is often caused by a sheared flywheel key. If a mower blade hits a rock, the flywheel key shears to protect the crankshaft, which throws off the ignition timing. We can replace your flywheel key on-site.
Over time, valves stretch and wear, changing the clearances between the rocker arms and valve stems. This causes hard pulling, loss of compression, and starting issues. Regular valve adjustments prevent this.