372xp won’t start.

[Craigb]

 

Air leak. Flywheel side is good but I might do the bearings seen as I’m so deep into it.

[Craigb]

Should there be a seal between the oil pump and the casing? Also my plastic oil pump drive gear doesn’t have an ear on it like the ones I’ve seen on L and S, is that an issue?

[spudulike]

The screws on the oil pump seal it as they are through holes. The leaks you have are pretty typical in old machines, they probably won't interfere with running unless the saw is in the edge of the carb max revs tuning it the fuel mix is oil lean or old.

Not sure what "the ear" is but the oil pinion should have a single sided arm that slots in to the clutch drum cut out or the pinion will have two arms ( like a propeller) that slot in to the cut outs on the drum. If the pinion has no arms, it will not oil.

I am pretty sure that what you have found won't stop the engine running.

 

[Craigb]

No arm and no propeller. I need a new pinion then. 

[adw]

I agree, that is not enough leak to stop it firing up, I have been trying to find what the 02 ignition unit fits but am struggling, the 01 does fit the 576 but does not appear in any 372 parts list, there has to be a very simple reason why this machine does not fire, I am begging to think this may be an ignition unit issue.

[Craigb]

When I comes to the crank seal, do you put it on the crank sleeve first and then into the case or put the sleeve on the crank and then install the seal? 

[Craigb]

Also I’ve heard of an o ring sitting under the sleeve, mine doesn’t have on as it appears many don’t. Would a smear of sealant like hylomar blue on the crank help?

[spudulike]

7 hours ago, Craigb said:

When I comes to the crank seal, do you put it on the crank sleeve first and then into the case or put the sleeve on the crank and then install the seal? 

I used to put the seal on the sleeve and then slide both on to the crank and fit the seal....carefully. If you fit the sleeve and then the seal, there is a risk of damaging the seal or dislodging the seal spring.

You can use the factory seal fitting sleeve and did develop my own method of fitting seals on cranks with stepped shafts and have never heard of anyone else doing it so it is my little secret😉

 

Your idea of sealing the sleeve with a bit of sealant is fine as the sleeve doesn't need to rotate on the crankshaft. I think I often used a bit of heavy grease to seal it in the past and what you have is as I would expect on an old 372.

[spudulike]

19 hours ago, adw said:

I agree, that is not enough leak to stop it firing up, I have been trying to find what the 02 ignition unit fits but am struggling, the 01 does fit the 576 but does not appear in any 372 parts list, there has to be a very simple reason why this machine does not fire, I am begging to think this may be an ignition unit issue.

With my deerstalker on, I would deduct that the coil has been on the saw for a long while so would reckon it was someone pulling and swapping parts to make one saw work and that crap around the coil means that the saw has been running for a long while like this.

You know that that coil case type was used on most 3 series machines with the HT lead length, rev limits and ignition advance ramp up being the only differences with most bring swappable without any perceivable difference in operation. 

I reckon it is probably OK.

If the saw has compression...150+psi and a fat spark, the carb/ fuel system is probably at fault. 

Get the airleak sorted then check the impulse, fuel line and carb.

The fuel line in these machines do split where they push through the fuel tank wall. Easy to check with a mityvac...plug one end and pump it up to check for leakage.

AND, don't use the decomp valve on starting...this machine and the 395 used to give me issues on starting after big rebuilds so did without them on the first start.

[adw]

10 hours ago, Craigb said:

Also I’ve heard of an o ring sitting under the sleeve, mine doesn’t have on as it appears many don’t. Would a smear of sealant like hylomar blue on the crank help?

There should be a very fine o ring under the sleeve, they all, and should have it.