I have a seized upper chain tensioner, and have just read the thread about freeing it using carb cleaner, penetrating oil etc. At this stage, the head is still on mine (4.2 XJ) what are my chances of freeing it without removing the head? Obviously I would rather not if at all possible.
Will the plunger pin depress fully such that you’re certain it isn’t what’s binding? If that’s not it and the oblong shaft is actually gummed up, I wonder if carefully removing toothed plate, plunger, and spring and heating and cooling the shaft a few times might do it, before having to resort to contaminating chemicals.
The plunger is sticking too, but not what is causing the issue. I’ve removed the serrated plate and had a bit of a go in there, but no joy. I wondered about using heat, but getting it in through the breather opening fills me with dread. Worth a crack, I guess. Back in the day, removing a head posed no drama, but I’m not so keen these days. Scared I might snap a head stud.
Thanks for the suggestion
Using a bit of propane flame, directed at the sprocket, wont be an issue. This is where having the official adjusting tool would be helpful.
I agree, try a little heat…Just finished rebuilding an engine that had been in storage for unknown many years…the tensioner was very difficult to move to the point I actually bent the factory tool. But it did finally free up. JS
1 Like
Kevin,
What tool have you been using to try to loosen up the tensioner? Which direction did you try turning it?
Paul
This is my tensioner tool. I have set the engine with slack at both sides of the chain, but there is no movement of the adjuster in either direction. When the slack is taken up, the cams are timed correctly; there’s just too much slack in the back run.
Jeff, did you free it up with the head still on?
I was able to free it up, but it took a lot of pressure, but once it started to move, it got easier. I did not have to remove the head, just more pressure. Just keep in mind that the tensioner can be installed in either direction, so it may be opposite to what you think as far as how to apply tension. You my want to remove the “pin” just to make sure its not locking on to the sprocket. JS
1 Like
I’m worried about shearing off the pins on the tool, with attendant damage to my knuckles 
plus bits dropping into the engine. Perserverance will win out I guess, I’m just hoping for an easy way out.
BTW I always stuff the cavity with rags to prevent stuff dropping in, but it’s still a fraught process.
1 Like
I would definitely remove the pin as Jeff suggests and investigate why it is also sticking as you reported. You might have burrs on it or on the adjuster plate teeth. Be careful neither it or the spring don’t fall into the netherworld. Then I’d put the plate back on and try turning again with the tool. Definitely don’t force it so hard the tool’s pin breaks off or we’ll hear you yelling in this hemisphere.
If still no go, I’d try a judicious amount of heat applied to the shaft after removing the plate again. Repeat the attempt a few times, then break out the chemicals. It’s up to you if you change the oil after that assuming it frees up. No telling what’s in that stuff.
I assume you’ve seen the insides of that intermediary gear and shaft before. There really isn’t much to it, and only so many ways it could bind. There is a sludge trap in the back side of the shaft and I was rather grossed out by what I saw inside mine.
Update, and success! Finally built up the nerve and applied some heat, no go. Poured some acetone into the cavity above the front part of the adjuster holder ( there is a small hole to allow oil to drip onto the eccentric adjuster) and let it soak for a while. A bit of force later and bingo, freed up. One happy camper and an adjusted upper chain. Thanks to all for the advice. 
3 Likes