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what could happen with the timing belt?


Strato_54
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I'm not the best at working on engines and mechanics yet as i am still learning (15 almost 16) but i do know for a fact the the VG33E is an interference engine and that if the timing belt breaks on these types of engines it could do some serious damage. If my timing belt snaps on this engine, what are the possible things that could result coming from that happening. I saw somewhere that some pistons have grooves in the heads deep enough so that if it does break that even if the valve was open it wont do any damage and all you would have to do is replace the timing best. Is this the case and should i worry changing the belt right now. I do believe it is the same belt from factory (97) with only 90k on it. If i let it break is there a good chance it wont break anything serious or do i have to change it now.

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The valve reliefs on some engines are deep enough to make them non-interference. The Pathfinder VG33 is not one of those engines. The valve reliefs and the small cam profile mean the valves don't spend much time in harm's way, so your chances of a piston meeting a valve when the belt fails are lower than they could be with some other interference engines. I've read a few accounts on here of people getting lucky and getting away with just replacing the belt. (Keep in mind though that this definition of "lucky" still has you stranded until you can get it fixed.) If you don't get lucky, and a valve does meet a piston, the valve bends and doesn't seal anymore. When you replace the belt, you'll have no compression in that cylinder. Replacing valves means removing one or both cylinder heads (depending on how many valves are damaged).

I got my '93 without a service history and replaced the timing belt myself (using the service manual and this writeup) before I started driving it. If its prior belt changes were done at the recommended service intervals, the one I removed probably had another 10k miles left in it, and it looked okay when I removed it. But I'd much rather do a (comparatively) small job on my schedule and have it over with than have it crap out without warning at a time/place of its choosing, get it towed, and then have to tear it down to a short block to repair it.
 

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If the timing belt breaks, depending on the conditions at the time it breaks, RPM, engine load and other factors, at the very least you may get a bent valve. There are other possibilities such as piston damage, camshaft damage and other components.
Timing belts are designed stronger to your average fan belt and last alot longer. I ran one truck I had 160k miles before changing the T-Belt and when I removed the original belt, you could still read the OEM part number on it. I would just inspect it and check for wear.

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2 hours ago, Manik said:

If the timing belt breaks, depending on the conditions at the time it breaks, RPM, engine load and other factors, at the very least you may get a bent valve. There are other possibilities such as piston damage, camshaft damage and other components.
Timing belts are designed stronger to your average fan belt and last alot longer. I ran one truck I had 160k miles before changing the T-Belt and when I removed the original belt, you could still read the OEM part number on it. I would just inspect it and check for wear.

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so if i had the original belt on it, even just inspecting and if i can see its still in good shape (again this engine has next to no heavy use other then commuting around at this point) i can just leave it alone. but only if then but if its in noticeably bad shape i would obviously change it. This kinda what youre saying? some people say change them every 7 or so years and the manual says about 160k i believe so theres different opinions. if its in good shape would you say just leave it even if its the factory one?

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2 hours ago, Slartibartfast said:

The valve reliefs on some engines are deep enough to make them non-interference. The Pathfinder VG33 is not one of those engines. The valve reliefs and the small cam profile mean the valves don't spend much time in harm's way, so your chances of a piston meeting a valve when the belt fails are lower than they could be with some other interference engines. I've read a few accounts on here of people getting lucky and getting away with just replacing the belt. (Keep in mind though that this definition of "lucky" still has you stranded until you can get it fixed.) If you don't get lucky, and a valve does meet a piston, the valve bends and doesn't seal anymore. When you replace the belt, you'll have no compression in that cylinder. Replacing valves means removing one or both cylinder heads (depending on how many valves are damaged).

I got my '93 without a service history and replaced the timing belt myself (using the service manual and this writeup) before I started driving it. If its prior belt changes were done at the recommended service intervals, the one I removed probably had another 10k miles left in it, and it looked okay when I removed it. But I'd much rather do a (comparatively) small job on my schedule and have it over with than have it crap out without warning at a time/place of its choosing, get it towed, and then have to tear it down to a short block to repair it.
 

if it leaves me stranded what ever its not hard to call my dad and get a trailer. and as long as the chances of the engine doing serious damage if the belt snaps is pretty low then im happy. i dont really have the time or energy right now to replace it and i just wanna see if i will be able to let it go for a little bit longer.

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i just realized from my last reply that i dont give a fskc if it leaves me stranded in the middle of nowhere as long as the engine is ok thats what i care about wow lol

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A visual inspection would not be a bad idea. Look for cracking on the back of the belt and evidence of oil or coolant leaks from the cam/crank seals and water pump. The spec in the manual is around 105k IIRC. I haven't found an age limit from Nissan, but seven years sounds reasonable. Yours is old enough to buy beer. Good luck!

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If it were me I'd change it.  It's definitely more robust than a regular belt, but at the end of the day it's a 22 year old piece of rubber, I wouldn't trust it for much longer. You certainly wouldn't trust 22 year old tires!

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If it were me I'd change it.  It's definitely more robust than a regular belt, but at the end of the day it's a 22 year old piece of rubber, I wouldn't trust it for much longer. You certainly wouldn't trust 22 year old tires!

Definitely change it. Parts are less than $200. If you can do the work yourself it’ll save several hundred dollars.

Mjo: I’ve been trying to get a hold of you for a few days. PM me!


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4 minutes ago, Astrorami said:


Definitely change it. Parts are less than $200. If you can do the work yourself it’ll save several hundred dollars.

Mjo: I’ve been trying to get a hold of you for a few days. PM me!


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Just replied.

 

And agreed about the level of work. I'd never done more than suspension and brakes prior to this job and didn't find it difficult to do on my 4Runner, just a little time consuming because I went slow and careful.

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  • 3 weeks later...
  • 7 months later...

truth be told i have not yet changed the belt but it has been going strong. took it out for a cruise the other day to get the fluids moving and accidentally over revved it passed 4k on the up shift but none the less belt has held on. BUT i still plan on changing it. The question came into my head of when i do change my belt should i go aftermarket belt such as Gates or should i go OEM nissan belt. what is over all a better made belt, does anyone have a preference or does it just not matter along as its not a no name from amazon 

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44 minutes ago, adamzan said:

I have used aftermarket belts without any problems. But the OEM ones have perfect alignment marks and are only a few dollars more.

so basically what ever i can get my hands on. gotcha 

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Strongly recommend a full kit. Belt, tensioner, water pump, cam seals, front main seal, and new key for the crankshaft sprocket. The real expenses in the timing belt replacement is the labor, book is something like 5.2 hrs. You really don't want to have to go back in there in a few months when the water pump fails or an oil seal starts leaking. Not replacing the $1 key has wrecked 3 engines I knew personally, first one of them was mine. 

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39 minutes ago, Mr_Reverse said:

Strongly recommend a full kit. Belt, tensioner, water pump, cam seals, front main seal, and new key for the crankshaft sprocket. The real expenses in the timing belt replacement is the labor, book is something like 5.2 hrs. You really don't want to have to go back in there in a few months when the water pump fails or an oil seal starts leaking. Not replacing the $1 key has wrecked 3 engines I knew personally, first one of them was mine. 

Ok woah woah woah hold up. Are the seals a km thing or like the older the are the more brittle they get. I was just planning on doing belt only since it’s only got 90,700 km on the motor. I guess seals makes sense. But what key are you talking about?

 

EDIT: never mind i know what key had a slow moment there. but rest of my question still stands is it a must or not really? if i can get away with just belt hey right on but if its a yeah i slightly encourage the full kit then ill just do that. and i have to go to nissan again at some point this week for a washer fluid pump for our armada

Edited by Strato_54
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I skipped the crank seal on mine because I didn't have one and it wasn't leaking yet, and the damn thing started leaking like crazy as soon as I put it back together, bad enough that I pulled it right back into the shop, tore it back down, and ordered a new seal. When I helped a friend do the timing belt in his dad's Kia, we skipped the water pump. I didn't like it, but we didn't have a new one, and it seemed alright. A year or so later the pump bearings locked up and tried to kill the engine. Point is, the parts are old, their failure could take out the engine, and you're in there anyway. Just because they've gone 90k without issue doesn't mean there's another 100k (or another 20 years) left in them.

 

I think I used a Gates belt when I did mine, along with a new tensioner pulley, cam seals, crank seal, water pump, thermostat, and water pump bypass hose. I also replaced the lower rad hose (didn't like the look of it) and the hose coming off the bottom of the thermostat housing (don't remember why, but I probably destroyed it trying to get it off). I did not however replace my crankshaft keys. They looked fine and showed no signs of wallering out their keyways. I suspect they only get chewed up if the crank bolt isn't torqued properly, but don't quote me on that.

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I was looking at this listing here but it doesn't appear to come with the seals or the keys. if its a super strong reccomendation that i get the seals front main, cam shaft and what not then ill do that since it looks like rock auto is cheap as dirt compared to my local lordco. what would be a full list of things to change in here? So far ive got the following in my head, add or remove what ever from here:

 

Cam seals

Crank seal

water pump

tensioner

belt obv.

all the keys what ever those look like

 

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When I bought my Pathfinder (1993 SE) in 1999, it had 128k miles on it with no records of any maintenance on it. I figured to replace the timing belt just for safety sake. A year and about 10k miles later, had the water pump lock up in Sam's club parking lot. I was just picking up stuff for a week of camping that my family did every year for the 4th of July week. Told my mom that I would fix my truck and meet up after. Got the truck fixed there in the parking lot but did turn into a long day of disaster that wound up stressing me and me getting to camp a day and a half late. About 6onths later, I was back in there again because I developed oil leaks from the seals. Oil and rubber are not good together.  A couple years later, the sprocket key chewed out the keyway in the crankshaft leading to the cam timing to go out. I patched it up with JB Weld and got a almost a year more before it got very bad and the valves and pistons introduced themselves to each other. By that time I had rounded up a replacement engine and had the fun of swapping in a 3.3 from an Xterra that had taken a side trip in a R50 before it got to me. 

 

Long story short, would have saved myself a lot of time and money if I had simply spent an extra $60 when I had first replaced my timing belt. That key after taxes cost me a whopping 97 cents at the local dealership. For the cost of a dollar, I destroyed a rather expensive engine that wound up costing me about $900 and many hours. 

 

While in there, makes sense to replace rubber and moving parts. Hoses and thermostat are right there, easy to get to while apart and cheap, why not replace them then? 

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50 minutes ago, Mr_Reverse said:

When I bought my Pathfinder (1993 SE) in 1999, it had 128k miles on it with no records of any maintenance on it. I figured to replace the timing belt just for safety sake. A year and about 10k miles later, had the water pump lock up in Sam's club parking lot. I was just picking up stuff for a week of camping that my family did every year for the 4th of July week. Told my mom that I would fix my truck and meet up after. Got the truck fixed there in the parking lot but did turn into a long day of disaster that wound up stressing me and me getting to camp a day and a half late. About 6onths later, I was back in there again because I developed oil leaks from the seals. Oil and rubber are not good together.  A couple years later, the sprocket key chewed out the keyway in the crankshaft leading to the cam timing to go out. I patched it up with JB Weld and got a almost a year more before it got very bad and the valves and pistons introduced themselves to each other. By that time I had rounded up a replacement engine and had the fun of swapping in a 3.3 from an Xterra that had taken a side trip in a R50 before it got to me. 

 

Long story short, would have saved myself a lot of time and money if I had simply spent an extra $60 when I had first replaced my timing belt. That key after taxes cost me a whopping 97 cents at the local dealership. For the cost of a dollar, I destroyed a rather expensive engine that wound up costing me about $900 and many hours. 

 

While in there, makes sense to replace rubber and moving parts. Hoses and thermostat are right there, easy to get to while apart and cheap, why not replace them then? 

fair enough but right now its a matter of more money out then in as our 6 leaker blew a head gasket and took out the HPOP and other stuff along with it, armada needs a slough of parts and the pathfinder is kinda the least amount of priority. But then a again with it being 90k km it hasnt met the full service schedule and its been sitting for the most part for the past 8 years or so maybe 7 and like driven from the garage to the drive way every 4 months until i took it over. so it would make sense to change all this stuff while im here since its been sitting neglected. i will do thermostat since rock auto is cheap as dirt it seems as for hoses i might take my chance on that one since they are still in good condition as it doesnt see ANY road use as i still have to get it inspected. it should be on the road properly around august maybe july. i do understand the job but just dont know the exacts of this motor, and basically im replacing everything that i remove to get to the belt. this week ill probably order everything such as thermostat, cam and crank seals, belt, tensioner, water pump, keys and i think thats all that i can think of. i have to replace the rad here soon so ill probably do the hoses when i do that job

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Ok so heres my shopping list. lower hose for pipe to rad and engine to pipe upper hose, spectra rad since i screwed mine, gates thermostat 2 beck/arnly front cam seals 1 front fel pro crank seal and GATES TCKWP249 water pump belt and tensioner. that is my current list of new shiny things from rock auto because my auto parts store is way expensive

Edited by Strato_54
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If you're replacing any hoses, the bypass hose is the one to do. It can be done afterwards but is a pain to get to. If the rad hoses are in good shape you can probably leave them. I've never replaced the key on any of mine, but that's not saying I've done things right either. The cam and crank seals have bit me in the ass like Slartibartfast as well. My crank seal started leaking 3 months after the job and of course before a long weekend road trip was to take place lol.

 

The parts are pretty cheap on rock auto, so if you can stretch it I would just do it all.

 

@Mr_Reverse aren't the keyways only an issue on the earlier VG's? I've never had a problem with any of mine, but they are all 94 and up. I do recall several people having issues with the (basically square tooth belt time frame) versions. I'm pretty sure they changed the design at one point. The VG33 style is definitely different.

Edited by adamzan
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