Help need good advice timing chain

[jeff huffman]

I need a opinion on a 32000 mile original. I am doing spring cleaning on a new to me 87 gn. Thoughts on installing a timing gear set? Does it need a new one at this milage and age? Will be driven maybe 1000 miles a year. Just cruising and maybe at track once or twice for base line times. Car will remain number matching and original. Thanks for any help you could offer.

 

[Nick Micale]

,,,,,,,,,, and maybe at track once or twice for base line times. ....................

Based upon some recent original 30 year old timing that I have replaced, that part of your statement above would result in my opinion of a resounding YES, replace the chain set.

The issue I am concerned about is not the chain, but the nylon or plastic teeth on the cam gear which will not only shows wear, but also many small cracks all around the gear.

Normal driving even with some boost would not be a concern to me, but WOT blasts for a sustained period would load the plastic gear much more than normal, or even just spirited driving.

If the gears ended their life at WOT you will not only replace the timing set, but also be removing the heads to replace valves.

In the early years I replaced a few original timing sets at 50-60K miles on GN's that were driven so hard the chains became loose enough to contact the timing cover because the teeth on the gear would be worn down almost to the metal part.

 

[earlbrown]

Yep. At this point mileage means nothing as the youngest TR out there is right at 30 years old. It's a wear item and it's surpassed it's lifespan.

 

[mikes86ttop]

Give Nick a call. He will set you up...Mike

 

[McGuyver]

This is on my list too for an original with 10k miles. If I want to go back with the oem style plastic tooth cam gear, who make a good one? Should the crank gear and chain be replaced too? Part numbers required would be appreciated. On the while you are at it... Are Earl's oil mods recommended for one remaining stock? Thanks


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[earlbrown]

At 10K most likely all you need it the top gear.


....and I would severely recommend Earl's mods;.

 

[No disintegrations]

But no matter what RPM if the the timing set fails there will be a least several bent valves. I was in a gn years ago and it ate the chain tensioner rolling from a green light. Bend bend bend. Push car out of traffic. Sad.

 

[Johnnie]

I am in the same situation Jeff is. 31k mile stock GN and want to update the timing chain. But, is there a recommendation as to what to buy and vendor to purchase one?

Next question.... Can a "qualified mechanic " , aka one that has a good rep for quality work , do the work without issue or special training? The reason I am asking is that we all know that our cars are kind of peculiar and that a "Buick" guy should ideally be the one wrenching on it.

The guy that changed out my body bushings was meticulous, cautious as hell and thorough. He also builds / repairs motors, brakes, diffs and that kind of stuff ..... Just not Buick 3.8's. I don't really know of any Buick engine gurus around here...

 

[No disintegrations]

I am in the same situation Jeff is. 31k mile stock GN and want to update the timing chain. But, is there a recommendation as to what to buy and vendor to purchase one?

Next question.... Can a "qualified mechanic " , aka one that has a good rep for quality work , do the work without issue or special training? The reason I am asking is that we all know that our cars are kind of peculiar and that a "Buick" guy should ideally be the one wrenching on it.

The guy that changed out my body bushings was meticulous, cautious as hell and thorough. He also builds / repairs motors, brakes, diffs and that kind of stuff ..... Just not Buick 3.8's. I don't really know of any Buick engine gurus around here...

He should be good if he does axles, motors etc.

 

[earlbrown]

I am in the same situation Jeff is. 31k mile stock GN and want to update the timing chain. But, is there a recommendation as to what to buy and vendor to purchase one?

Next question.... Can a "qualified mechanic " , aka one that has a good rep for quality work , do the work without issue or special training? The reason I am asking is that we all know that our cars are kind of peculiar and that a "Buick" guy should ideally be the one wrenching on it.

The guy that changed out my body bushings was meticulous, cautious as hell and thorough. He also builds / repairs motors, brakes, diffs and that kind of stuff ..... Just not Buick 3.8's. I don't really know of any Buick engine gurus around here...

I like the crappy stock plastic coated timing set. You just have to replace it every 25 years or 150,000 miles, whichever comes first.

On the timing chain, any decent mechanic can swap it out. I would recommend doing my oil mods to the cover while it's off and lapping the filter adapter flat.

Along with swapping out the stock oil pickup to a Melling unit while he's cleaning the teeth out of the pan.

 

[McGuyver]

Earl, thanks for the comments. I will read up on this and may tackle it myself this summer. If I am not up to the cover mods I will buy one of yours or send you my cover if you do that. Looks like GM discontinued the cam gear awhile ago. Does Cloyes or Melling make a good oem style plastic tooth gear that will mate up to the oem chain?


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[Nick Micale]

Earl, please do not take offense to my post here as it is my opinion.

My first comment is about the stock plastic timing gear set. If you purchase a original chain set from GM is it going to be an original from GM stock of 30 years ago, or is it recently made from an unknown source in the US or abroad?

Anyway, why the hell would you want to replace a plastic gear vs. a billet steel gear? If plastic will last 150k miles, a billet steel gear will last twice as long under the same conditions. The cheap, crap timing sets use a cast or powder gear which may last 5k-10k miles.

The second comment is about having someone take apart a stock, low mileage oil pump if you have no issues with it now? Is your original engine and oil pressure is fine, if so there is no reason to chance someone screwing it up.

If you plan performance mods to significantly increase HP and RPM, or are re-building your engine, it may be prudent then. Many original GN's have gone 150k-250k with a stock turbo oil pump.

The oil pump problems I have seen are when after-market parts are used, or someone screwed up working on the cover. Just this week a customer had an oil pressure issue, and it turned out the replacement gears had a failure with a rebuilt pump gear set? Not the time first I have experienced this.

 

[earlbrown]

I guess our experiences vary greatly. Years ago I lost my factory plastic timing set at 150,000 miles driving down the interstate. I towed the car to work in put in a billet timing set, lapped the filter adapter flat and smooth and put my car back together.

At that exact instance my magnetic drain plug went from coming out clean to coming out with a big 70's style afro on every oil change. (back then I drove the GN over 600 miles a week back and forth to work so oil changes were frequent)

Fast forward another 100,000 miles and the billet set stripped out again. Turns out when that one failed, it took out my timing cover's gear pocket and chewed hell out of the filter adapter. I got a new GM cover, modified it for more efficiency (and took pictures for a ''how to'' article), and spent the money for the 'crappy plastic coated aluminum gear'.

At that exact instant my drain plug started coming out clean again.

After that my car was stolen, beat to hell, ran without coolant then sheared off the bottom of the cam sensor until the engine was literally destroyed. I could reuse that timing set if I wanted to.

If I were to ever build an engine with a flat tappet, I would re-use that set.

 

[fastblackracing]

I am in the same situation Jeff is. 31k mile stock GN and want to update the timing chain. But, is there a recommendation as to what to buy and vendor to purchase one?

Next question.... Can a "qualified mechanic " , aka one that has a good rep for quality work , do the work without issue or special training? The reason I am asking is that we all know that our cars are kind of peculiar and that a "Buick" guy should ideally be the one wrenching on it.

The guy that changed out my body bushings was meticulous, cautious as hell and thorough. He also builds / repairs motors, brakes, diffs and that kind of stuff ..... Just not Buick 3.8's. I don't really know of any Buick engine gurus around here...

John, the best advice I can give you is to do your homework first to help your mechanic be successful with your timing chain replacement.
And by that I mean You should be familiar with whats needed to do this and if you have the proper procedures printed out to share with him it will go much better for both of you.

• To best change the timing set He will need to remove the tin cover over the torque converter, remove the crossover pipe and then the oil pan comes off. The pan is removable with the engine in the car just remove the 20 bolts and sometimes you need to rotate the crank a bit to give the pan clearance to slide by the rods.
• The reason to remove the pan is 1 you can clean out any debris that is in the bottom such as timing gear teeth and whatever else And 2 if your rear main seal is leaking now you can have a new one installed.
• Also the way that our timing cover forms the seal area for the front of the oil pan, it can be tricky to get the cover and gasket in and sealed properly if you leave the oil pan on while you try to install the timing cover.
• It only takes about 1 hour to remove the oil pan and this is really the way to do it,
• Removing the timing cover is straight forward stuff but there are a few things on reassembly that are critical. 1 The oil pump must be packed with grease before re installing so the oil pump will prime itself. 2 The crankshaft balancer bolt can be a mother to get torqued down properly at 240# feet of torque......if this is not tightened correctly it will come loose and cause you grief.....broken balancer, crank gear, etc.....Very important... and any more I use a small amount of blue loctite just to be sure. Some guys will just use the impact wrench on it and use loctite as well.....This is a big 3/4" -16 thread bolt and it must be tightened down, I cannot stress this enough for someone that is not familiar with our cars.
• There is a specific procedure for setting the timing of our cam sensor once it has been removed and it is easy to install It 180* out of sync and have the car run, but not properly again easy to do this if you are not familiar with these cars.
• http://vortexbuicks-etc.com/cam_sensor.htm
  
• If you go armed with good information to Help your mechanic understand the specific things our T/R cars need It will help him and you out.
• I have seen this seemingly easy task end badly before when the it was not done correctly, and I just wanted to offer up some things I have learned over the years that might help you out.

 

[jeff huffman]

Based upon some recent original 30 year old timing that I have replaced, that part of your statement above would result in my opinion of a resounding YES, replace the chain set.

The issue I am concerned about is not the chain, but the nylon or plastic teeth on the cam gear which will not only shows wear, but also many small cracks all around the gear.

Normal driving even with some boost would not be a concern to me, but WOT blasts for a sustained period would load the plastic gear much more than normal, or even just spirited driving.

If the gears ended their life at WOT you will not only replace the timing set, but also be removing the heads to replace valves.

In the early years I replaced a few original timing sets at 50-60K miles on GN's that were driven so hard the chains became loose enough to contact the timing cover because the teeth on the gear would be worn down almost to the metal part.

Nick I think I am just going to replace the nylon gear set with a melling stock gear set per the way it will be driven is mostly mild street. Question is do I still need to replace or even run a tensioner and should I use a stock thrust spring or a roller button? I haven't found a roller part number at this point. any thoughts would help.
Thanks

 

[flyhigh]

napa cam button npt95189 tensioner npt95158

 

[bigballsbilly]

I have a new in box Cloyes timing chain I never used if anyone is interested.

 

[SS/GN]

Nick I think I am just going to replace the nylon gear set with a melling stock gear set per the way it will be driven is mostly mild street. Question is do I still need to replace or even run a tensioner and should I use a stock thrust spring or a roller button? I haven't found a roller part number at this point. any thoughts would help.
Thanks

Be careful with this, I have installed some timing chains and gears on other engines and the quality of the gears and chains is terrible. They stretch and the gears wear within miles of driving. What used to be acceptable years ago is junk today. Do the billet gears for sure. The T/A silent chain and billet gear is what we use to call a premium stock replacement. The hardest part about playing with cars today is getting good parts. It is easier to do it right once.

 

[Johnnie]

A lot of interesting stuff here. Fastblackracing , I appreciate your advice, my mechanic does too. He is a pretty good wrench, but my GN is his first. ( he cut his teeth on turbo audis, Beemers, and lots of other complicated stuff) I know it may sound like I am taking a chance on him, but the young man is thorough , extremely meticulous, and doesn't attempt to fix anything he doesn't know about. Timing chain is going to be midsummer ( going to be a "stock" replacement because mine is a low mile non racer) . Next is the vacuum brake swap, BTW.
Thanks, again.