I am working on a Rover raider with a tecumseh Ov358ea 13.5 engine.
It has had issues starting since I've had it, in fact I've never got it running. It will turn over but fail to fire and then cough out of the intake.
I though it may have had a stuck valve but have check the valves and adjusted the clearances (they were within tolerance anyway) but still no good.
I now think it may be a head gasket or the fly wheel key has sheared so my first question is:
What does correct ignition timing look like regarding the coil and the magnet? I understand that a few degrees advanced timing is ideal but does the following picture suggest too much advancement??
For context the engine is currently at TDC and both the intake and exhaust valves are closed.
Yep tried starter fluid to no avail. I pulled the head off and broke the head gasket in the process, not supprisingly.
There was significant carbon build up which I cleaned and polished and then put it all back together. It coughed and idled for about 2 seconds before stalling again.
Hopefully the local has a gasket kit for these tecumsehs
You may be lucky to find a gasket, they have been out of production for many years now though. Does it have good consistent spark? Not impossible that it is the coil itself. A quick google says 10-35 degrees btcd so that looks ok.
Personally i would have started with a compression test, than a leak down test to rule out mechanical. one other check is valve timing, easiest test for that is at TDC (not comp stroke) the both valves should rock.
Good spark from the plug but I will try a new one just in case. I should be able to compression test it when I get my kit back tomorrow (leant it out).
It does surprise me a little that non OEM tecumseh parts don't seem to feature in Google searches for spares....
Out of curiosity what did you set the valves to? a bit of research online is telling me that valve clearance is critical on these. I do vaguely remember having a similar problem with one but was many years ago. According to the manual it should be a very tight .004" on both intake and exhaust
Tecumseh shut down production in 2009, and yeah unlike briggs and honda aftermarket has so far not really gone anywhere. We struggled to get genuine parts 10 years ago.
I am not a big fan of the tecumseh engines at the best of times
OK, it's not the spark plug. Strong blue spark clearly visible.
So it getting spark, It's got plenty of compression and it's getting fuel directly (ill worry about the carb after ive got it to urn over/idle momentarily)
I went back to the flywheel key thinking that it may have sheared to the point that it was 180 degrees from where it should be and I just didn't realise when I first inspected it.
Unfortunately it is not the case. After removing the flywheel the key is still in perfect condition.
The stator is very dirty however and wondering if a dirty stator can reduce its performance?? 🤔🤔🤔
I've taken the exhaust off and tried it on the off chance it was clogged - same result.
Leak tested the head with coloured water and determined there is no blowby occurring at the valves as the fluid remained constant for 15 mins and towel underneathshowed no coloured water.
No scoring or abrasions on the cylinder and the head gasket is still in ood condition.
Something obvious we are missing here. Have you checked the cam timing, making sure the valves are opening and closing in the right sequence relative to TDC?
Don't worry about pulling it apart to check the cam timing, just get it up on compression stroke then rotate the motor through its cycle to make sure the exhaust valve starts to open after it has gone over TDC and follow it through the cycle of the exhaust valve shuts and the inlet valve begins to open. Probably best to check with the head in place, doesn't matter about the gasket at this stage
