Timing Chain Housing - Repair or Replace Chain Ramp Pins

[Gordo2]

Gents,

Looking for some input.

One of the pins that is press fit into the timing chain housing dropped out - the chain ramps mount to the pins.


Search turned up:
-Some folks repair by cleaning and JB welding the pin back in place. No long term feedback on how they held up. The fitting in the housing doesn't appear to be wallowed out, but won't know until I find the pin (assuming its in the case).

-Others recommend replacing. I searched but couldn't figure out which housings are compatible with the 3.2L (years that are interchangeable/part #'s for left side housing). If I replace it will be a used housing, I'd rather not buy the wrong part. Also wondering how I can confirm condition of a used case (is it uncommon for the pins to fall out?).

Thanks, Gordo

[Flat6pac]

The compatable housings would be the 930 casting number. 930 part number units will be 3.0/3.2 application and aluminum, they are all the same.
Bruce

[yelcab1]

PM me if you want a housing from a 3.2L engine.

[K Sykes]

My understanding is they are originally glued in with an epoxy with metal filler, which is what JB Weld is. Look at the other side of the case and you'll see a smear of it at each pin.

[KTL]

Originally Posted by K Sykes

My understanding is they are originally glued in with an epoxy with metal filler, which is what JB Weld is. Look at the other side of the case and you'll see a smear of it at each pin.

Yep they are pressed in and the epoxy on the back of the chain box is key to avoiding a leak. Lots of people think they have leaky cam seal or rocker shaft(s) when it's actually either the chain tensioner & idler arm post or the chain ramp post(s). The original epoxy gets old and cracks off and there's your leak source. Or the post comes out........ Much less common for the post to fall out!

[Costa P]

Hi Don,

I've had the exact same problem!
Epoxy... Really??

I recovered the pin out the bottom of the case, through the oil drain plug (I had to fish it out with long nose pliers). The pin survived the trip without a single mark or any damage!

My mechanic modified the pin by drilling and tapping it's back end with M4 thread and also silver soldering a shoulder onto it. We then pressed it back into the housing with Loctite (yes it needed to be pressed back in, yet it fell out all by itself in the first place!).

If the the press fit with Loctite 603 (high strength retainer, suited for retaining press fits and oil tolerant) fails to keep it secure, its got the shoulder to stop it from falling out and the M4 centre bolt (also with Loctite) to keep it from falling into the engine. That sucker is not going anywhere now!!!

I'll take some photos and post them as soon as I have a chance.

[Gordo2]

Thanks for the input guys,

I'm taking up Yelcab1 on his offer to sell me a used box.

Gordo

[Gordo2]

I didn't see it when I pulled the drain plug originally - must have rolled there and stuck to the magnet as I flipped the motor around on the stand.



I'm picking up a used housing but think I could have reinstalled the pin.

It won't fit in the hole - would need to freeze & press it in. I think pressing it back in with a bit of epoxy in the hole would have done the trick.

Meanwhile the idea of a metal pin coming loose in the timing chain box, or anywhere inside the engine is enough to ward off the idea...

[Costa P]

Hey Gordo, your pic with the pliers and pin is deja-vu! Hehe!
...let me guess, you too had to pry it past the oil pick-up screen, in order to pull it out through the oil drain hole!

What are the chances, that both of us had the exact same (apparently rare) problem!
And in both instances, the darned pin is still a tight fit in the housing....yet it fell out by itself!

[Walt Fricke]

One benefit of the earliest style sump plates and pump screens was the screen could be removed with the plate, giving you quite a bit of room to fish around inside the case for bits and pieces.

[Gordo2]

Originally Posted by Costa P

...let me guess, you too had to pry it past the oil pick-up screen, in order to pull it out through the oil drain hole!

CostaP,

Couldn't have described it better myself - tried to pull it out with a magnet, then resorted to the pliers to pry it out.

Even stranger is that the pin fell out in a location that could have thrashed the engine (if it got caught between a chain and sprocket), yet it just dropped out and rolled to the lowest point - leaving nothing but gaping, oil spewing hole as evidence (the ramp still supported the chain even with the 1 pin).

Definitely an odd failure.

Gordo

[Costa P]

Originally Posted by Gordo2

Even stranger is that the pin fell out in a location that could have thrashed the engine (if it got caught between a chain and sprocket), yet it just dropped out and rolled to the lowest point

Gordo

Gordo, I couldn't agree more. I still remember vividly, that moment when I poked the epoxy and realised that the pin was gone!

I must reiterate though, that back in the other thread ( Epoxy... Really??) Walt pointed out

Originally Posted by Walt Fricke

I'm not too surprised that nothing worse happened before you caught it. Generally, stuff which gets loose in the case sits down in the bottom, drawn toward the screened pump area, and doesn't cause problems. Like valve lash adjusting nuts, or broken pieces of the elephant feet. Though exceptions to this might be disasterous.

And your tensioner was still keeping the vibrations down to a dull roar. And at least one pin held the ramp more or less in place.

The hair on the back of my neck is standing right up!
Gordo, both of us experienced the same freak incident and both times luck was on our side.

[otto_kretschmer]

I had the same problem with my 76S. The pin worked its way loose on the right side and almost fell out. It elongated the hole. I used JB Weld and it was still working six months later, but I didn't feel comfortable with this bandaid repair so I bought a new casting from some LA recycler in the Burbank area.

Putting the new casting in was fun..

[Gordo2]

Although I purchased a good used timing chain case to replace the one that the pin fell out of - I have decided to repair the original one.

Why? Because after researching press-fit pins, I'm reasonably confident that it can be repaired.

The hole on my case appeared to be in perfect condition - the pin would not insert in ambient air temp. If the hole or the pin appeared damaged in any way, I wouldn't have been inclined to give this a shot.

I found that Loctite sells various adhesives for pin retention - each made to match the particular type of stresses/loads or operating environment that the pin experiences. I selected Loctite 609 (~$15) for the job.

I used 600 grit sandpaper on the lower part of the pin - to rough the surface. This was recommended by Loctite to increase adhesion. I then cleaned it with isopropyl alcohol:



For interference fit pins, Loctite recommends heating the hole instead of freezing the pin - since freezing can cause condensation which could negatively affect the adhesive.



After ~ 10 minutes of heat, I was able to get the pin started in the hole. I applied the Loctite 609 to the pin, pushed it in the hole as far as it would go, and tapped it the rest of the way in with a brass drift. BTW - It appears the hole is tapered, you can't get the pin to insert from the outside of case when heated.



The pin inserted with a nice tight fit:


To finish up, I applied Loctite 9340 (JB Weld equivalent that came with my Supertec sealant kit) to the backside of the pins.



If I ever stop sidetracking and put my engine back together... time and mileage will tell how well the repair worked. Meanwhile, I'm confident it will be fine.

Side note - I had the cases chemically cleaned and blasted by the place that does my powder coating. Love the rough natural aluminum finish. I plan to coat it with Boeshield T-9 when everything's buttoned up.

Gordo