Need help fast....engine may be jacked

[Mauitrailguy]

To make a long story short, my brothers 90 broke down on the way to my house. I brought it home and began to trouble shoot. I started with the timing because the way it was acting. While doing the timing I got it all set TDC and reset the timing belt that was only a tooth off. After using the crank bolt to spin the engine a couple times to get the slack out I went to remove the crank bolt. When I turned it left the crank turned left but not the cam or the timing belt pulley on the crank. There is no resistance when turning either way. Thoughts?

[devonianwalk]

Is the keyway on the balance shaft intact?

[ahardb0dy]

what he said , can you tell if just the pulley is turning or the crank too?

[Mauitrailguy]

Is the keyway on the balance shaft intact?

 

 

what he said , can you tell if just the pulley is turning or the crank too?

 

 

just pulled it off. Key is sheered. Do i find one and put it all together or say F#@% it and swap? I have another 90 here that runs-ish.

[devonianwalk]

Depends if the valves have kissed the pistons. The easiest way (without pulling the cylinder heads) to tell would be to replace the key and do a compression test on a couple of the cylinders. My TB jumped a tooth on one cam and two/three on the other. My motor is still running strong today.

[ahardb0dy]

On my 87 hardbody the key sheared twice and no internal damage was done. You need to inspect the groove the key sits in, if it is damaged the only real way to fix it would be to weld in new metal than shape it so it is correct. When it happened to me the second time, my mechanic at the time suggested replacing the engine, reasoning that if we had to pull the engine apart to replace the crank, with the miles I had on the engine who knew what else we may find, so I bought a JDM engine and he swapped it, ran better than new with that engine !

 

Should mention after the first time, he installed a new timing gear, damener, crank bolt, and key, tightened it all to spec and about 2 months later the same thing happened. Had to replace the timing gear and damener because the groove the key goes in was chewed up on both parts.

 

The early VG30 engines only used one key for the timing gear and the damener, later engines had a seperate key for each part.

Edited September 9, 2013 by ahardb0dy

[bushnut]

such a small part to fail, yet creating so much trouble. what would cause this?

[ahardb0dy]

could be if the crank bolt was loose causing movement, or if it worked it self loose, ?? As I said there is only one key on the early VG30 cranks about .50 to .75 long and two parts share half of that, the timing gear and dampener, not really a good design but I guess it works pretty good, besides myself I only have heard of the OP that has had this happen.

 

Before it happened to me nothing was ever touched as far as the crank bolt so it wasn't left loose, so who knows why??

[Mauitrailguy]

The key is completely sheered and the crank has damage to it in the direction of spin. I have read up on using some loctite 660 to mend the keyway. The cranks has two keys on this rig, one for the crank timing sprocket and one for the dampner. The original plan was to put the engine from the two door(failed key) into this 4 door 90 I have because my brother has kids and he told me the engine ran good. I have my doubts about the engine in the 4 door. the check engine light is on and it blows some smoke. I might be able to salvage the 4 door engine then fix the 2 door engine on my own time. What is a JDM engine and how much do they run for?

[ahardb0dy]

It may have been just the 87's had one key. I thought the 88 was the same?? I had an 87.

 

Is your truck with the spun key an 88 or a 90? I'm confused.

 

I don't think I would trust the Loctite product to fix the crank,

 

A JDM engine is an engine taken from a vehicle from the Japanese market, (JDM = Japanese Domestic Market) supposedly the inspections are so strict over there that car/truck owners are encouraged to buy a new vehicle rather than spend what they have to to get their older vehicle inspected. So the vehicles engines and trannys are removed and sent over here to be re-sold as a low mileage engine, most JDM suppliers claim the engines have less than 60K miles on them.

 

I have bought 2 JDM VG30's, the first one looked brand new when I got it, the freeze plugs were clean and gold, under the valve covers the rockers had a slight gold glow to them, it looked new, my mechanic at the time was very impressed with the condition of the engine. It ran perfect and felt very strong.

 

The second JDM engine I bought and the one currently in my 94 pathfinder wasn't as clean but it did have the Japanese "pitwork (Nissan's performance brand name in Japan) oil filter on it so I bought it, it runs perfect.

 

Usually depending on where you get the JDM engine you can get one for around $700 .