Camshaft Chain Tensioner

eddohawk · February 13, 2011, 01:38:23 PM

Hi all

Have read a few posts in here regarding needing to have the tension rod fully extended and the one way cam facing down when reinstalling the tensioner. When I was installing my tensioner I had to push in the tension rod in 2 or 3 notches to allow the housing bolts to thread in. Is this ok?
or does it suggest that my chain does not have enough slack in it. Note that all of my camshaft sight marks (bearer cap dots are visible through the holes and timing punch marks marks) are correct. TDC is ok to.
Thanks in anticipation.

Regards

Mark

andyb · February 13, 2011, 01:54:11 PM

If it was fully extended when you put it in, that'd mean that it was out of adjustment completely.

The manual says to set it to a set spec length, bolt it in, and then put the springs in it.

racerrad8 · February 14, 2011, 09:54:52 AM

Quote from: eddohawk on February 13, 2011, 01:38:23 PM
Have read a few posts in here regarding needing to have the tension rod fully extended and the one way cam facing down when reinstalling the tensioner.

The tensioner should be fully compressed when installing it. After the bolts are in and the tensioner is tightened against the cylinder block, the center spring(s), copper washer and bolt should be installed. The spring pressure is what applies the correct tension on the chain. You are right about the one-way cam being installed down.

Quote from: eddohawk on February 13, 2011, 01:38:23 PM
When I was installing my tensioner I had to push in the tension rod in 2 or 3 notches to allow the housing bolts to thread in. Is this OK?

NO...Take it out, fully compress the tensioner and then install it. The follow the above directions...

With the tensioner fully compressed you should be able to put the tensioner body against the block by hand. If you used the screws to tighten the tensioner to the block, you have just put the chain under a ton of stress and ultimately stretch.

Randy - RPM

eddohawk · February 14, 2011, 12:34:40 PM

Quote from: racerrad8 on February 14, 2011, 09:54:52 AM
Quote from: eddohawk on February 13, 2011, 01:38:23 PM
Have read a few posts in here regarding needing to have the tension rod fully extended and the one way cam facing down when reinstalling the tensioner.

The tensioner should be fully compressed when installing it. After the bolts are in and the tensioner is tightened against the cylinder block, the center spring(s), copper washer and bolt should be installed. The spring pressure is what applies the correct tension on the chain. You are right about the one-way cam being installed down.

Thanks for this.....my Clymers manual says that the tensioner rod needs to 'stick out of the housing by 35.5mm' before I install it.

So as I understand what your saying is that the tensioner rod needs to be fully compressed and not sticking out of the body prior to install and that after I bolt into into the block, install the spring and tighten the end cap this will push the tensioner rod and tension the chain?
Thanks heaps

Gazza · June 27, 2011, 03:57:27 PM

Hey guys, I have been trying to get mine back in but it just does not seem to want to seat correctly.

I've tried it with the tensioner fully compressed as Randy says and also with the tensioner at 1.4 inches out per the Haynes and in both cases I cannot get the springs to go into the housing far enough to put the cap bolt on unless a whole heluva lot of force is used, and then it seems to be so much force that I decide it can't be correct. So I'm just holding off until I hear from a pro.

What am I doing wrong? Thanks for direction!

Gary

FJ1100mjk · June 27, 2011, 07:52:04 PM

A couple of weeks ago, I went through the installation process after having my cams out.

The knob on the end of the shaft was, I think, deformed from pushing up against the rear chain guide. When I looked at the Haynes manual, it said to put the tensioner opposite (pointing up) from what the deformed knob looked like it should, and that tipped me off that the Haynes manual was incorrect, as was the callout for the shaft to be extended 35.5mm.

I ended up compressing the shaft completely, then installing the tensioner without the spring. It never did sit completlely flush with the cylinder, and I had to tighten (not very hard) the mounting screws to seat it to the cylinder. After that I put the spring and cap on, which was a real bear. I turned the motor over by hand numerous times to check the cams timing, and everything moved/rotated fine. I have yet to fire it up, so I have my fingers crossed.

Gazza · June 27, 2011, 08:05:53 PM

Thanks. The only thing I recall the Haynes saying in regard to up vs. down was that the ratchet portion should be down. I didn't really pay attention to the shape of the contact knob v/v how it hits the rear guide. You may have a good point!

JMR · June 27, 2011, 08:28:24 PM

Just a question...has anybody else had the rubber "tip" off the tensioner eaten away? Could be secondary to heat, miles etc etc. I had one ready to break off the metal bar. It was chunked etc. Several big burn outs, 20 dyno runs and about 40,000 miles..... nothing really awful. If that tip comes off the bar it cannot take up all the distance. I will not use an APE piece....ever. The contact patch is minimal and it is a lousy "solution". I hate those things.
I'd recommend that people occasionally remove the tensioner and check it out. It is easy to do so especially when doing a valve adjustment.

racerrad8 · June 28, 2011, 01:45:33 PM

Cam chain tensioner 101...

Okay first off, to answer JMR, the rubber tip is subject to compression, wear and breaking off due to heat and age. The tip acts as a dampening/compression unit to absorb chain harmonics due to came rotation. If the rubber tip is gone, the metal backing plate is still there and the tensioner has enough stroke to keep things tight. (they fall/break off the racecar engines all the time without any issues)

I do not recommend removing the tensioner for inspection as if for some reason the cams are in a position to rotate backwards; it can jump time.

With that said the tensioner should always be installed with the ratchet down. This is important as if it is installed incorrectly the tensioner just keep ratcheting out by the harmonic vibrations which eat the rubber right off the chain guides before breaking the chain.

So, if everything is installed correctly in regard to the camshaft timing the tensioner, with the plunger fully compressed, will sit against the block and not have to use the mounting bolt to get it seated. I have found a few that are off by about .020 or the thickness of a second gasket. If there is a gap it should be filled by adding a second gasket. If you don't all you are doing is compressing the rubber tip which leads to early failure.

After the tensioner has been installed the springs, copper washer and retaining bolt need to be installed. Somewhere around 87-88 they change the design of the nut and made it more than twice as long to help get it started. When using the short nut it takes quite a bit of force and coordination to compress the spring and get the nut started. I have found using a tee handle, extension and socket are the best tools for the job since a ratchet usually will not ratchet...

And finally...when you have it all installed you need to turn the engine over in reverse using the 22mm hex on the intake camshaft. That allows the chain to slack on the slack side and set the proper tension. If you listen carefully you usually hear 1-2 clicks from the tensioner.

Gary, as long as the tensioner was flush with the mounting surface, put the springs in and button it up.

Randy - RPM

Gazza · June 28, 2011, 02:23:26 PM

Thanks for your help, Randy, I'll give it another go.

I did notice that there were two gaskets previously installed -- they were put back as found.

This bike is an '89 ... maybe they used an older/shorter nut ... or maybe there's another type of nut involved elsewhere in this process.

JMR · June 28, 2011, 03:05:54 PM

Quote from: racerrad8 on June 28, 2011, 01:45:33 PM
Cam chain tensioner 101...

Okay first off, to answer JMR, the rubber tip is subject to compression, wear and breaking off due to heat and age. The tip acts as a dampening/compression unit to absorb chain harmonics due to came rotation. If the rubber tip is gone, the metal backing plate is still there and the tensioner has enough stroke to keep things tight. (they fall/break off the racecar engines all the time without any issues)

I do not recommend removing the tensioner for inspection as if for some reason the cams are in a position to rotate backwards; it can jump time.

With that said the tensioner should always be installed with the ratchet down. This is important as if it is installed incorrectly the tensioner just keep ratcheting out by the harmonic vibrations which eat the rubber right off the chain guides before breaking the chain.

So, if everything is installed correctly in regard to the camshaft timing the tensioner, with the plunger fully compressed, will sit against the block and not have to use the mounting bolt to get it seated. I have found a few that are off by about .020 or the thickness of a second gasket. If there is a gap it should be filled by adding a second gasket. If you don't all you are doing is compressing the rubber tip which leads to early failure.

After the tensioner has been installed the springs, copper washer and retaining bolt need to be installed. Somewhere around 87-88 they change the design of the nut and made it more than twice as long to help get it started. When using the short nut it takes quite a bit of force and coordination to compress the spring and get the nut started. I have found using a tee handle, extension and socket are the best tools for the job since a ratchet usually will not ratchet...

And finally...when you have it all installed you need to turn the engine over in reverse using the 22mm hex on the intake camshaft. That allows the chain to slack on the slack side and set the proper tension. If you listen carefully you usually hear 1-2 clicks from the tensioner.

Gary, as long as the tensioner was flush with the mounting surface, put the springs in and button it up.

Randy - RPM

Good to know there is enough stroke...thanks. I agree about jumping time but shim under bucket engines always require the tensioner to be removed for shim changes so I personally don't think it is a big deal. I run SOB in my FJ so it comes out. On a separate note....I have thought about starting another thread concerning 13mm SOB retainers and problems with retainer well "egging" with both Kibblewhite and APE Ti retainers. I have had retainers Ti nitride coated but think DLC or something else would be even better. Have you run into this problem and found a bullet proof solution? Do the 9.5mm shim retainers also egg. Obviously they are lighter but does the retainer maintain a tight fit in regard to the shim OD?

racerrad8 · June 28, 2011, 06:40:34 PM

Quote from: JMR on June 28, 2011, 03:05:54 PM
On a separate note....I have thought about starting another thread concerning 13mm SOB retainers and problems with retainer well "egging" with both Kibblewhite and APE Ti retainers. I have had retainers Ti nitride coated but think DLC or something else would be even better. Have you run into this problem and found a bullet proof solution? Do the 9.5mm shim retainers also egg. Obviously they are lighter but does the retainer maintain a tight fit in regard to the shim OD?

I don't have any experience with shim under bucket, so I can't be of assitance.

Randy - RPM

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Camshaft Chain Tensioner