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998 Engine Build - Can't Turn It 360


Best Answer Rorf , 05 July 2018 - 05:48 AM

Could be crankshaft hitting the central oil pipe in the gearbox, but definitely the crank webs hitting something in the gearbox. If pistons were hitting valves the crank would not turn 359 degrees either direction.

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#1 Big_Adam

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Posted 04 July 2018 - 03:09 PM

Evening.

 

Very slowly building a 998 engine. All fairly standard. Got the crank bearings ground, new rings, nothing fancy.

 

Built the block up, no problem. All span well. Stuck the gear box on and didn't think to turn it over till today when I was putting on the flywheel, now I can't turn the stupid thing over.

 

It seems to turn 359degrees then hits something. Seems to be around the bottom stroke of 1 and 4 cylinders (you can turn it till it stops, go all the way back, then it stops at about the same place). Going to pull it apart Friday and have a root about, but any ideas what I should look for?

 

Ta for any advice.

 

 



#2 minidaves

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Posted 04 July 2018 - 03:21 PM

what gearbox is it on?



#3 Big_Adam

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Posted 04 July 2018 - 04:00 PM

what gearbox is it on?

 

Well ... I bought it from Guessworks ... 10+years ago. I assume a 998 gearbox. The correct one. It matches the cases for the 3 others I have for some reason.



#4 Dusky

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Posted 04 July 2018 - 04:43 PM

Sounds a bit like debris in 1 of the gear teeth.

#5 Big_Adam

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Posted 04 July 2018 - 04:57 PM

Sounds a bit like debris in 1 of the gear teeth.

 

Ah see, the gearbox is attached with bolts, but the ... primary gear (top one the flywheel sits on) isn't in. The gearbox is just on with bolts.



#6 Ethel

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Posted 04 July 2018 - 08:55 PM

Does it stop near TDC? Piston hitting sparkplug or a valve?

Ignore if you span it freely after fitting them. Noting the crank angle where it clunks will help though.

Starter motor bolt is another classic.

#7 Retroman

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Posted 04 July 2018 - 09:13 PM

Ok bit confused....as you say the primary gear is not on...? ...the gearbox is irrelevant

 

Can't understand why you would have the flywheel on without the primary gear

 

A 998 should never have a crank / gearbox clearance issue

 

I assume then you are talking about the engine not turning

 

I also assume the head / rockers etc are on and the cam in

 

Could be the cam timing out far enough so that a piston and exhaust valve are making contact

 

or a cam lobe and conrod (not sure on a 998 but can on 1275's)



#8 Rorf

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Posted 05 July 2018 - 05:48 AM   Best Answer

Could be crankshaft hitting the central oil pipe in the gearbox, but definitely the crank webs hitting something in the gearbox. If pistons were hitting valves the crank would not turn 359 degrees either direction.



#9 Bat

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Posted 05 July 2018 - 07:24 AM

Hi,

If it's at the bottom of the stroke it sounds like it's hitting the gbox.

Was this before or after fitting the flywheel?

Try removing the bolts inside the flywheel housing to see if that frees it up.

Cheers  :proud:



#10 scoop-deluxe

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Posted 05 July 2018 - 10:28 AM

Work your way back with whatever you bolted on last.
Could be something silly like fuel pump bolts being too long or distributor drive not in all the way!

#11 Retroman

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Posted 05 July 2018 - 01:08 PM

A 998 is considerably shorter stroke than a 1275 with smaller big ends too and should never be anywhere near hitting the gearbox.

 

As its happening with pistons top and bottom the crank is no where near the gearbox as the webs are near vertical

 

It can't be the crank / cam either for the same reason



#12 Wizzalong

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Posted 05 July 2018 - 07:00 PM

My distributor drive would jam the engine as it lifted out whilst turning over (without distributor fitted) try taking drive out and turning?



#13 russo

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Posted 05 July 2018 - 09:51 PM

Sounds like conrods hitting gearbox casing. What gearbox you using?



#14 Big_Adam

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Posted 06 July 2018 - 09:01 AM

Ok bit confused....as you say the primary gear is not on...? ...the gearbox is irrelevant

 

Can't understand why you would have the flywheel on without the primary gear

 

A 998 should never have a crank / gearbox clearance issue

 

I assume then you are talking about the engine not turning

 

I also assume the head / rockers etc are on and the cam in

 

Could be the cam timing out far enough so that a piston and exhaust valve are making contact

 

or a cam lobe and conrod (not sure on a 998 but can on 1275's)

 

I've never been a man to make much sense. This is all from "if I just do it, even if I F'it up. At least I've done it" rather than leaving it for 10more years.

 

1 - Gear box on, no turn. Gearbox off, turns fine.

 

2 - I am not a smart man.

 

3 - Aye, thats what I thought, but here I am.

 

4 - Crank won't do a complete 360 turn with the gearbox on.

 

5 - Nope. Thats future me problem.

 

6 - See 5

 

7 - See 1.

 

Could be crankshaft hitting the central oil pipe in the gearbox, but definitely the crank webs hitting something in the gearbox. If pistons were hitting valves the crank would not turn 359 degrees either direction.

 

And ding ding ding we have a winner. Its hitting the center oil pickup ... now how the F do I fix that?


Edited by Big_Adam, 06 July 2018 - 09:10 AM.


#15 Big_Adam

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Posted 06 July 2018 - 09:53 AM

Far as I can tell, its catching on the bolt for the conrod. Like ... could brute force it past, but would ruin the pickup levels of catching.

 

mXgwZ2P.jpg

 

So do I heat and beat on the pipe, or is there a different shaped pickup I can get?






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