HJ60 2H, are they a interference motor - ie, get the timing wrong &...

Submitted: Sunday, Sep 27, 2015 at 11:00

ThreadID: 130420 Views:3266 Replies:3 FollowUps:8

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LandCoaster

We are doing the imfamous rear timing case oil leak in a 60 which involves removing the timing gear... We have a prob in that previous to dissambly the timing marks of all cogs will not line up as per the FSM assembly, we've cranked it 30 times so far.
So we are thinking of just pushing forward but if we get it wrong - Of the HJ60 2H, are they a interference motor - ie, get the timing wrong & youll smash pistons, vavles, rod & lifters? - huge thanks for any help...

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Reply By: Ross M - Sunday, Sep 27, 2015 at 12:07

Sunday, Sep 27, 2015 at 12:07

All diesels have almost no piston to head clearance, ie, they are high compression 16:1 12HT and around 22:1 2h.

Get it wrong and it will destroy something or many things.

The timing gears are clearly marked and should be easily placed in the correct timing positions especially if you have a Factory manual. In mine, it shows a schematic diagram of all related rotation components.

If you have already rotated the engine multiple times it must be in synch otherwise it would be caressing other essential items. You can of course have the pump timing way out and not in synch as it only works in concert with the engine as well as synched for correct operation.

Any crashing usually results in bent valves and guides, broken rocker gear.

Always MANUALLY turn ANY 4 stroke engine 2 complete turns to ensure there is no collisions before ever cranking it. Failure to do that often results in wet handkerchiefs.

AnswerID: 590790

Follow Up By: LandCoaster - Sunday, Sep 27, 2015 at 12:47

Sunday, Sep 27, 2015 at 12:47

yep, agree with all above.

I just wish the assembly timing marks would cycle around. That they are not means the is an odd sized cog in the timing train, perhaps the cam cog, cause it's an aftermarket turbo on it. There is other evidence of high-end tuning like massive exhaust & quality fitments.

An odd sized cog it may be, however if the pump has been advanced one tooth to overcomve timer wear and/or tweak this aftermarket turbo 2H it wont reassemble correct. I will be looking at a myriad of reason as to why it is running rough.

So far my best solution is to set is as per fsm, TDC on right stroke, mark the five cogs and reassemble in that order...That seems to make more sense than twisting the IP, crank and cams around to factory, it left the factory a long time ago...

FollowupID: 858827

Reply By: Ron N - Sunday, Sep 27, 2015 at 13:09

Sunday, Sep 27, 2015 at 13:09

Landcoaster - The 2H is definitely an interference design engine. I cannot see how anyone could install a different-sized gear in the timing gear train, it would wreck all the timing.
It's more likely that one or more timing marks are out because someone used an aftermarket gear or gears that were not marked from the factory, and they then marked them incorrectly.

Cheers, Ron.

AnswerID: 590796

Follow Up By: LandCoaster - Sunday, Sep 27, 2015 at 13:44

Sunday, Sep 27, 2015 at 13:44

opps, in the OP i shorted out "differant size cam and idler cog", there is two idelrs allowing a reduction of one set...
I thought about incorrectly marked replacements too, but then the cog stampings are same across all 5 cogs, are the same as some images ive found and how/why it is runnnig so well...
Ive read once, but only once, that the assembly timing marks rarely line up or take many many cycles to line up.
Im worried 'cause i've seen images of others lined up in there "assembly state" per-diassembly.

FollowupID: 858831

Follow Up By: Ron N - Sunday, Sep 27, 2015 at 13:49

Sunday, Sep 27, 2015 at 13:49

"or take many many cycles to line up."

You've nailed it right there. It can take up to nearly 200 revolutions in some engines, that have numerous gears in the timing case, before all the timing marks line up again.

FollowupID: 858833

Follow Up By: pop2jocem - Sunday, Sep 27, 2015 at 14:11

Sunday, Sep 27, 2015 at 14:11

What Ron said. It's been many a long year since I had my fingers in a 2H so memory not good enough to give a definite answer regarding that particular setup. However many engine timing gear trains use 1 or more of what we use to call a hunting gear, in as much as the crankshaft gear and camshaft gear always obviously keep the same relationship timing wise but an idler gear may very well take 100 or revs before the original marks line up.
Set the engine to TDC usually No1 on compression and see if any marks on the cam gear line up with any marks on the timing case.

Cheers
Pop

FollowupID: 858836

Follow Up By: mike39 - Sunday, Sep 27, 2015 at 14:23

Sunday, Sep 27, 2015 at 14:23

The situation you are referring to is called a "hunting tooth" gear train.

When you align all the timing marks up with no.1piston at TDC, then rotate the engine you will see marks on the intermediate gears not aligning with other corresponding gear marks but the 2 important gears, crankshaft and camshaft will be in perfect alignment with where they are supposed to be.

The system is designed so that gear wear is evenly distributed over the service life of the unit.

Good reliable engines, those old 2h/12ht
mike

FollowupID: 858837