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4jg2 engine rebuild

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Re: 4jg2 engine rebuild

Postby snapper » Tue Aug 19, 2014 1:19 am

scruff123 wrote:what do people use as a wieght for tensioning the timing belt?


The first time I changed the timing belt on mine (4JB1TC) I just grabbed the bathroom scales, weighed up a few bricks to get the right weight (9kg) then tied them together with a length of cord and tied that to the tensioner. Gave the belt a 'tweak' or two to get it level and did the bolts up.

Second time round went up market and got one of those cheap electronic fish scale things off fleabay and attached one end to the tensioner and the other end to the bashplate with a small bottle screw and then tightend the bottle screw up until I got the reqd 9kg
This posting may have been helpfull, on the other hand probably not... Either way, I may have had drink when posting it in which case it's probably not as helpfull as it could have been....
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Re: 4jg2 engine rebuild

Postby danz20 » Fri May 01, 2015 6:52 pm

snapper wrote:
scruff123 wrote:what do people use as a wieght for tensioning the timing belt?


The first time I changed the timing belt on mine (4JB1TC) I just grabbed the bathroom scales, weighed up a few bricks to get the right weight (9kg) then tied them together with a length of cord and tied that to the tensioner. Gave the belt a 'tweak' or two to get it level and did the bolts up.

Second time round went up market and got one of those cheap electronic fish scale things off fleabay and attached one end to the tensioner and the other end to the bashplate with a small bottle screw and then tightend the bottle screw up until I got the reqd 9kg



ha ha I did one last week and used an old 10lt oil container filled with 10lt of water on a hook worked well
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Re: 4jg2 engine rebuild

Postby greenwolverine » Fri Nov 27, 2015 4:57 am

I have a parts vehicle and just took apart the engine, which was dead

Crank is badly scored on one rod journal. No bearing material left on the rod. What a waste.

Manual says it can't be machined.
Any advice?
If anyone has a good crankshaft for me in the region of $150 (I'd have to pay shipping to Canada on top of that) that would be wonderful.

Another thing: the round part with three arms that the cam pulley bolts onto has a ring worn in it. Can those parts be sourced anywhere or is the answer to sleeve it?
Many thanks
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Re: 4jg2 engine rebuild

Postby geeves » Fri Nov 27, 2015 7:18 am

aliexpress have listings for crancks new but no genuine. Make sure its nitride treated and it should be ok
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: 4jg2 engine rebuild

Postby greenwolverine » Mon Nov 30, 2015 1:38 pm

Thanks
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Re: 4jg2 engine rebuild

Postby greenwolverine » Sun Jan 31, 2016 12:15 pm

I managed to get a very good used crank off a 4JG1 from an industrial engines place.
Cranks are identical

Piston and rod to come, and then I'll have all the stuff I need for the bottom end

Reading the manual it says to tighten the rod bolts using engine oil to start them

Now the engine I'm rebuilding had a pair of rod bolts loose which caused all the problems, so I'm wondering how that would have happened in the first place

Wouldn't it be a good idea to use thread locker on the bolts?
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Re: 4jg2 engine rebuild

Postby Roderunner » Sun Jan 31, 2016 6:55 pm

The engine might have been rebuilt by someone using a dodgy torque wrench (who bothers to get their torque wrench recalibrated) , or it could have been a Friday afternoon job. I can't see any harm in using a thread locker sparingly if doing that inspires confidence in your rebuilt engine. There is also the possibility that the rod bolts were over stretched by previous over torquing, or even by over revving the engine as the pistons weigh a ton!
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Re: 4jg2 engine rebuild

Postby greenwolverine » Sat Feb 13, 2016 11:47 pm

THanks, and now a camshaft question
The 3 journal diameter readings are well within standard dimensions

One of my lobes is slightly below minimum height.

The wear on the tappets is in concentric circles as the book shows normal wear to look like. I have kept the tappets in order to match the lobes working on them.

Can I just reinstall the camshaft as is and live with a slight discrepancy in lobe height? I am not wanting a perfect engine, just one that can run again.
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