Tensioner Upgrade Question

TWJ · TWJ's Garage

I'm upgrading to the Carrera Oil Fed Tensioners for my '72 2.4 MFI engine and am trying to verify a needed part...

I've purchased used components so I don't have the benefit of a pre-packaged kit.

My understanding is that I need two (2) M8 X 60 studs for the top two holes on the left chain housing cover to replace the stock (shorter) ones. I believe these are part number 999.062.255.02 and are listed as "NLA" from our host...

SO... my question is: are these the correct replacement studs I need or is there something different? I've seen/heard some conflicting information.

Thanks in advance.

theiceman · 08-10-2009, 01:05 PM

go to a mtreic hardware supplier , they should be able to get you what you need.. But I would be wary putting " used " parts in such a critical area of the car in the first place.

Flat6pac · 08-10-2009, 03:12 PM

72 has 6mm studs and that all you will need, you might need a longer 6mm bolt with a larger washer to cover the 8mm hole but you chain boxes dont have the metal to tap 8mm AND there is no reason to,
Bruce

TWJ · TWJ's Garage

Here is a quote from the Pelican Tech Articles section that references to what I'm talking about (the same quote is in Wayne's book "101 Projects...") --->

"... Engines from 1967-72 require removal of the two upper studs on the left chain housing cover, and replacement with the two longer studs (M8 x 60)."

BUT I have had others suggest that the studs are M8 x 50 and other conflicting information.

This is what I'm trying to verify. I suspect Wayne is correct but just double checking on what I need to buy.

Thought's???

R_Builder · 04:50 PM

Just did this earlier this year. I decided to get longer studs from McMaster-Carr and build up some washers to cover the M8 hole....

In this application, it also works to pull the too-short M6 studs and use longer M6 bolts to close things up in these 2 locations. Since chain covers don't come off very often, you won't be exercising those mag threads enough to the point that the studs are necessarily the required "fix" here. I just chose to protect the threads in the chain housing for the long run...

If you want to go the stud route, I can did up the part number for them. As you can see, they are just the correct length for the job and the nut went to full torque no problem.

This is one of the rare cases where the Pelican catalog seems to have incorrect/incomplete info...

TWJ · TWJ's Garage

Thanks Doug (R_Builder)!

This is obviously correct.

Would you mind digging up the part number? It might also be useful for others looking to do this.

TWJ · TWJ's Garage

Doug,

Would that be the McMaster-Carr M6 stud part Number?

One other questions...are the bolts used to plug the hole where the oil temp sensor used to be anything special or are they just steel bolts to fit?

Thanks again!

ahdoman · 08-10-2009, 08:10 PM

Before you go to all this trouble; if you're using "used" parts make sure you try to prime and pump up the tensioners before installing. If they won't get hard, don't use them.

R_Builder · 08-10-2009, 08:57 PM

The McMaster-Carr part number for the M6 stud is: 98867A265 (M6x1mm pitch, 47.5mm long overall, not even a buck a piece). Put the short threaded portion of the stud into the chain housing (it has more than 1d engagement and like I said, it went to torque AOK) with red loctite.

For the life of me I can't find the thread I posted this info in when I was doing it. It was an add-on to someone else's. Maybe I put it in a "More Info" page for one of the parts...

The bolt/plug for the temp sensor hole(s) are kinda special from my perspective, and they require a sealing ring. Per PET (in the crankcase section for the 69-73 cars, shown as a plug for the temp sensor location on the case below the fan on the RHS), the plug is 900-124-002-02 and the sealing ring is 900-123-007-30. Double-check me on these as I already had some on hand and didn't have to order them. If the hole in the chain cover(s) is a 14mm thread, then these are the ones you need.

FWIW, I too started out with a used kit, so I kind of had to research things a little and collect the parts to put it all together. I was concerned, as others have mentioned, about the tensioners themselves so I tore them down, cleaned them up, made sure the bypass valves and over-pressure valves worked (with compressed air), then reassembled them, primed them, and did the install. Once you go through that exercise, you will see how relativily simple the PFT's are and why their reliability tends to be higher than mechanical tensioners (please, no need to open up that debate again... just my observations as I worked through the guts of the PFT's).

Hope this all saves you some time/heartache...

TWJ · TWJ's Garage

Thanks for all the great info.

It raised another question though...

How do I "prime and pump up the tensioners" to test them?

I think I have seen tensioner rebuilt kits as well, does that make sense?

R_Builder · 08-11-2009, 05:48 AM

You prime a tensioner by completely submerging it in fresh oil (yes it is a bit of a mess) and pumping the piston with your hand until no more air comes out the inlet port. At first you are just fighting the spring, then it will firm up some as the oil gets in and the air gets out.

Not sure they have rebuild kits for the PFT's. Other than a new spring and maybe a piston, not too sure what they could put in it. There are no internal seals in them like a brake master cylinder or brake calipers... you'll see. Just buy yourself new o-rings (that seal the inlet port to the chain housing cover) and new sealing rings for the hollow bolts and you should be good to go.

Now aren't you glad these used parts "saved" you all this money? I know, I know... my labor is free, too!

TWJ · TWJ's Garage

Hey...it's the journey that counts, right? I actually enjoy learning all of this...

Sounds like the internals of the PFT are pretty simple and therefore not much to go wrong. I'll do as you did Doug and disassemble them, clean, reassemble and test. Any tricks?

Here is the "repair kit" I was thinking off. It's off of Stoddard's website. Maybe is for spring tensioners only(???).

Repair kit for "049" & "053" tensioners, 1 req'd per tensioner. Fits 1965-1983.

$29.38

Item # 911-105-901-01

R_Builder · 08-11-2009, 11:56 AM

Yes, that is a repair kit for the earlier tensioners... PFT's start in 1984.

To take them apart, it is best to have a good vise to hold onto them. Then compress the piston far enough down to lock it out with the little pin (or use a nail or small screwdriver if you don't have the pin) so you can pop out the round wire clip that is on the top with some pliers. I used a c-clamp at this point to hold the piston down while I pulled the pin, then eased off the c-clamp to let the piston come out slow against the force of the spring. It is a pretty stiff spring, so watch yourself...

Indeed, it is all fun stuff to learn!