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Possible timing belt issue.


94TroutKiller
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Hello,

 

I am newbie to the site and I would like to start things off by saying thank you to all who have posted some very detailed info on this site which has helped me out quite a bit with my 94 Pathy XE. While I was driving home last night the engine just died on me and it would not start back up. My Pathy has 186,000 miles on it and was still running fairly well. I have already replaced the plugs, wires, cap and rotor. It has a new fuel and air filter and I replaced all the vacuum hoses. I have also removed the cat and installed a Flowmaster 40 series muffler because since it still had the original equipment and both were clogged. I have cleaned the MAF and installed a ground wire to the frame as well. I am not sure if the pathfinder still has the original timing belt or it has been replaced. Here is the kicker, I was attempting to set my timing and noticed the timing marks on the crank shaft pulley are only visible from underneath the vehicle (this is not good). I set the timing only by ear and checking to see the rpms were around 700. It ran fine for 2 days after the adjustment; the engine seemed to have come back to life. I know this was a no, no, but I needed a quick fix because I needed to get to work.

 

I had the Pathy towed home and then started trying to diagnose the problem. I checked for any lose wiring, vacuum hoses and clogged filters. I finally messed with the timing as I had marked the previous setting and I fired right up, well sort of. It has an obvious miss but it started. My question here is does anyone here think I am going to have to replace the timing belt? I know the life span on those suckers is around 60 to 105 K and is there any way that cam shaft pulley could have been placed on wrong or has my timing belt lost a few teeth? The only 2 items I have not changed myself are the O2 sensor and that darn timing belt…

 

Any insight would be greatly appreciated.

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It is possible to reassemble the crankshaft pulley such that the timing marks are in the wrong place unfortunately. It sounds like you have this problem. Of course this only makes it more hard to time your vehicle etc.

 

The good thing is your truck started again after it died. This means your timing belt didn't just snap... but you should really replace it if you don't know if it's ever been done and you have 186k miles! The change interval is 60k miles. It's only 100k miles if you have the rounded tooth crank and cam sprockets that came with the VG33.

 

When you change the belt you can fix the crank pulley to make timing it with a light easy. Alternatively you can find TDC another way and make new marks on your pulley...

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My question here is does anyone here think I am going to have to replace the timing belt?

Yup.

 

f you valuse the motor, do not drive it until you do this. If you don't know if the timing belt has been changed, assume it hasn't been although the fact that the crank pulley seems to be backwards indicates that someone has been in that far already. Your 1994 will have the rounded tooth sprockets and the recommended change intervals is 105k miles and every 4 years (my 14 year old belt still looked good at 97k miles).

 

The job isn't that hard so consider doing it yourself and there is a good write up by a Nissan mechanic in the Garage/How To section.

 

B

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Thanks for the quick responses!

 

On that note, I will be ordering the water pump, timing belt and tension pulley. This way I can have some piece of mind that these parts have been replaced by me and I won't have this issue for another 60k and avoid any serious engine damage. Hopefully I should have this done by the end of the week during my days off.

 

Thanks again for all help,

 

A

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You are welcome. Read up on the How To's first to make sure you have all that is required. Many people also change the thermostat and bypass hose because it is behind/above the upper cover/waterpump and also change the crank and cam seals since you are right there anyway.

 

B

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before you start tearing into it...run a compression check on all 6 cylinders...I got my tool from sears for like $80...its as easy as pulling all the plugs..screwing the right adapter in...turning the truck over a few times (make sure to pull the coil wire for safety...you may want to pull the fuel pump fuse too) you should have like 106psi i believe but if you have a dead cylinder it will show up like 60 or lower...if you find a dead cylinder don't panic yet if you have some mechanical aptitude and time

 

if a dead cylinder is found it's quite possible the belt jumped and you ate a valve or more...the square tooth belts are good for 60k i think and round tooth belts to 105k...I learned the hard way when i was 16 when i changed a water pump and not a timing belt...about 3-6 months later the belt snapped and i ate intake and exhaust valves in cylinder #1 and exhaust in cyl #3...

The extent of the work wasn't that much...pulling intake manifold,egr and then pulling the heads then disassembling the heads and replacing the valves after inspecting everything. The only specialty tools I needed was a valve spring compressor, torque wrench, 10mm alan socket and valve lapping kit...the entire job took about 2 days total...3 days b/c 1 of my valves was the wrong part in the right p/n box...with valves a complete engine gasket/seal kit and the tools and doing the work myself the engine work cost me ~$250-300 total

 

If you pass a compression check then i'd go ahead and change the timing belt and make sure I get everything right on it...def would change cam seals, water pump, t-stat, valve cover gaskets, and i'm sure theres something else i'm missing

 

 

EDIT: I saw you have a 94...taking the intake apart is a PITA...This is my gf's 95 tore down getting a timing belt and valve cover gaskets (i walked her through most of the work except when she got too cold and i did some work)

 

148309_751794720557_36619102_40784142_3133766_n.jpg

Edited by unccpathfinder
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Thanks for the quick responses!

 

On that note, I will be ordering the water pump, timing belt and tension pulley.

 

 

Good call on the tension pulley. I did not change that and almost lost my engine for the second time in as many weeks months. I should be punched in the face for not replacing it while I was in there. After my second timing belt mishap I am almost convinced that the VG33 engine is not an interference motor. I'm just not that lucky.

Edited by devonianwalk
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Great info...compression test, valve cover gaskets and cam seals along with the t-stat will added to the to-do list. Sounds like I am in for a fun weekend! And knowing that UNCCPATHFINDER only spent around 2.5 to 3 benjis makes me feel that much better. It sure beats having to dish out a crazy amount of cash for a new engine!

 

Thanks again to all!!

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Check with your auto parts store about "renting" the compression gauge. They will "charge" you the full price of the tool but, will reimburse you the full amount when you return it within a specific time. I had the benefit of borrowing one of my friends that happens to be a mechanic.

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devonianwalk, I am just as lucky as you in this department. My cousin owns a shop and I should be able to get a compression tool from him with no problem. If he can borrow my fishing gear, I am positive I can borrow a tool...

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You can't always trust the compression check if you are unsure of the belt condition.

When I first got my pathy I gave it the once over. I was sick when I found one cylinder with only 30 psi but figured hell I bought it as a hunting truck, it's just going to have to run like this for a while.

The timing belt was so loose it was slapping the cover when I would rev it. After changing the timing belt it ran so much better I decided to check the compression again. With the new belt it had a solid 180 psi per cylinder. The old belt could have jumped a tooth or was just stretched so bad the cam was lagging behind the pistons and the intake valve was closing too late. It was probably very close to hitting the piston.

I would replace the belt first then run compression. Unless you feel like doing it twice too.

James

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Another 'dead nuts' on method of determining if your valves are bent. Is to do a cylinder leak down test. Just roll the engine over until BOTH valves are closed, and pressurize the cylinder (through the spark plug hole) and check the rate in which the cylinder in question bleeds off pressure. It also helps to listen to the end of the exhaust pipe for excessive 'whistling or hissing sounds. It may be difficult on vehicles with a cat, however if you have any bent or leaking valves, it's pretty obvious by the 'whooshing' sound pouring out the tail pipe.

This kit sometimes comes with a compression testing kit.

 

Keith

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The old belt could have jumped a tooth or was just stretched so bad the cam was lagging behind the pistons and the intake valve was closing too late. It was probably very close to hitting the piston.

 

 

This was my case the first time I went into the timing chamber ("mud sick" thread). I neglected to change out the tensioner pulley which resulted in tearing my TB in half. After dodging the bullit TWICE I made sure to replace everything!

 

I once heard a guy say, "If you don't learn from your mistakes, why make them?"

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Actually, I think it was mid/late 1993 production year when they switched from square to round toothed sprockets but I don't have proof of that. 1994 and 1995 definitely have the round teeth, making the recommended replacement interval 105k miles instead of the 60k miles of the previous type.

 

B

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  • 4 weeks later...

Gents,

 

Well first and foremost I want to thank all of you who provided helpful advise on how to bring my 94 back to life. I know it took me a while but due to work I did not have much time these past 3 weeks. I managed to take a 4 day weekend and worked on my pathfinder. With all the info from you and with all the new parts it runs great, it's now ready to go back and do some fishing!

 

Thanks again!!!

 

94TroutKiller

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