Anyone cut a failed one open to see how they work and why they fail?

My TL is making noises like the belt is loose, complete with the early morning rattle if the car hasn't been used for a few days. I replaced the cam belt and idlers 13,000 km ago, water pump checked out ok and the tensioner wasn't leaking and was applying tension to the belt, so I left it in.

As far as I can tell, the tensioner is filled with a thick liquid, with the plunger attached to a disk with a small bleed hole or check valves to control fluid flow. A large spring pushes the plunger out.
I'm wondering if failure involves the spring breaking, the plunger rod letting go of the disc, the check valve(s) not working, or some chemical change in the fluid.

Possible internals?

http://t3.gstatic.com/images?q=tbn:ANd9GcSvk4gHqLJZdwPCJemOmRYa_pA2XRCV0 DCvOCQMjXUnF7qWuCFy

no but ill be pulling my one out soon, getting the morning rattle, turn off turn back on ticking gone.
normally comes back before engine warms up.

Same problem here just surfaced. Must be the time of year for this to happen. Early morning cold start, and I get the menacing rattle. Its only recently that my car now resides out in the open driveway and start up in the cold mornings may have something to do with it. Behaves itself any other time the car is started.
When I get the old one out, I will open it up to see if I can spot the problem.

It might just be in the really cold weather, the fluid inside turns to treacle, possibly. I'm trying to work out why mine does the Rattle of Death only when it's been parked for a minimum of two cold nights in a row and not driven in between, one night it's no problem. Definitely temperature related.

I will see if warmer weather helps, assuming it lasts that long. lol My daughter is driving it at the moment, she does about 3,000 km per month so it's not likely to rattle on her.

If it gets worse before then I will just have to rip into it again and replace it, no big deal.

Be nice to see what the problem really is with these tensioners.

There is a modified version for the 380 available, I think. How is it different and will it fit the 3.5L engines? (should do)

I too suffer from "the rattle". Have purchased a new one from Mitsubishi, just waiting for some free time really. Definitely a whole lot worse when the car has been sitting around for a few days! Turn the car off and on... hey presto its gone!

Weird or what? Definitely temperature related. My TJ is well behaved though, similar Km but no rattles. Actually, it has done 14,000 km less than the TL. Maybe the TJ will start rattling next? lol


http://www.3si.org/forum/f35/hydraulic-tensioner-nylon-shim-535787/

Worth a read. Nylon washer to stop the rod from retracting too far, as well providing a buffer to stop the rattles. Mmmm. . . .I want some!

The tensioner works a little bit like a damper, the spring pushes out the piston and the fluid dampens this. The issue is that the fluid over time seems to get too viscus thus when it gets extremely cold it is even worse and thus you get the rattle

The only way to fix is to replace. The 380 tensioner is all that is available now as all the part numbers have been superseeded

Madmagna, so we would use the 6G75 tensioner in all 6G7X motors?
Is it dangerous to drive the car if there is a cold start rattle from the tensioner?

An interesting read if you like technical info:

http://www.ntn.co.jp/english/products/review/pdf/NTN_TR73_en_P110.pdf

no but ill be pulling my one out soon, getting the morning rattle, turn off turn back on ticking gone.
normally comes back before engine warms up.

I am getting the same problem during the morning evey now & again have 190k on the clock on a TL. Will the 380 tensioner fit?

The auto tensioner is the same for the 24 valve 3.0L, 3.5L and 3.8L engines. So are the rest of the bits under the cam belt covers.

The auto tensioner is the same for the 24 valve 3.0L, 3.5L and 3.8L engines. So is the rest of the bits under the cam belt covers.
Thanks

Thanks

I just spent 30 minutes looking at an online parts catalog, the US Galant (our 380) and Diamante (our third gen Magna) with the 24 valve engines have the same part numbers for the various kits, so I'm fairly sure that is the way it is.

The auto tensioner is the same for the 24 valve 3.0L, 3.5L and 3.8L engines. So are the rest of the bits under the cam belt covers.

but not the belts

but not the belts

Source?

Source?

the 3.0 ltr has a 187 tooth belt and the 3.5 has a 195 tooth

the 3.0 ltr has a 187 tooth belt and the 3.5 has a 195 tooth

Oh, OK then.

Old versus new...old had a slight leak and weak tension...

https://lh4.googleusercontent.com/-5dpCzwWb-cs/UefR07Z9fII/AAAAAAAAAd0/or_T-RJtiWM/w1143-h857-no/P14694201.jpg

Weak tension?
That's hardly a sign the fluid in it has gone off, more indicative of spring failure.

There was a bit of play while it was bolted on, and there is a sign of a leak within the cavity. So I'd say the whole thing is stuffed. I don't understand how it managed to work...but it did sound bad in the mornings when starting the car. Either way I'm happy to change it over. I'm tempted to carefully break it open to see the internals.

EDIT: interesting reading about the sponge effect due to air entering which may have been due to the failed seal (small leak)...possible cause on mine...http://www.dayco.com.au/databank/documents/t000011.pdf

That is actually a load of rubbish guys, some brands claim this to cover their asses for warranty claims

I got a NTN one from Mitsubishi... Is it the same deal as a Koyo?

I got a NTN one from Mitsubishi... Is it the same deal as a Koyo?

No idea, other than to say "try it and see". lol

I've been trying to find out who makes the original tensioners for the days when mitsu engines were built originally, but no such luck.

A lot of cam belt kit suppliers talk as though they make them (eg Gates : http://www.gates.com/australia/brochure.cfm?brochure=7408&location_id=11308) but I bet there is a factory somewhere in Japan (or China, maybe Mexico or Korea) that makes them all, no matter where you buy the kit from.

Is the NTN brand name on the tensioner itself, or just on the box it came in?

Well I assume NTN is THE OEM supplier though Im aware Koyo is also a major OEM manafacturer... So Im wondering if maybe at some stage Koyo were the OEM and Mitsubishi switched? Or maybe some parts of the world Koyo make it and other parts NTN? Or Koyo simply make it because they can!
I would trust Koyo either way. Never knew Gates were an OEM manafacturer!

Wonder how much cheaper the Koyo HTs are! I still havent installed mine, though the time is coming near, I can feel it. Mine was 187$! Knocked my socks off :/ Though I like the phrase "do it once, do it right" (because I cant be fd doing it again).

Well I don't know what the issue was with the old tensioner, but the new one has solved my problems with the rattle at start up. I'm happy, and I can sleep easy at night.

Ntn has always been the manufacturer in all Mitsubishi motors which have used these units

Would you use a Koyo HT Mal?

I actually first experienced the clacking on start up when I came back from a holiday. Definitely notice it more when I havent driven my car for more than a day and on cold mornings. Look forward to that great feeling youre experiencing GTV! When it gets really bad or I find the time. Whichever comes first!

So do the Koyo or NTN tensioners have any markings on the body of the tensiioner?

I have one here, no markings at all. It has a separate end plate, peened to the body. The end plate has a code on it, WX100801. I'm wondering what make it is, and if it is even worth the effort to put on the car.

Well mine is clearly marked NTN and the bag it came in has the part number (1145A070) and says Made in Japan.
Not sure what end plate you are referring to? Whered you get yours from?
http://s2.photobucket.com/user/shezza84/media/20130721_124724_zps0cfd8c1d.jpg.html
I have read posts of aftermarket ones not lasting very long at all... So guess it comes down to how much you would dread redoing it.

Not sure what you end plate are referring to? Whered you get yours from?


It came in a Goodyear kit. No identifying marks on it and the water pump in the kit. Just packaged in clear plastic bags, no labels.
All the ones I've seen have solid alloy bodies, this one has an end plate peened onto the body at the far end of your picture. Don't think I will bother using it.

Now, to get a real one. lol

This is the one you have:
http://www.nitomainc.com/npsp3.php?masterno=1145A070

Never seen an end plate on a HT. Just a pin surrounded by a cavity and then a seal.
No identifying marks doesnt instill confidence! I wouldnt havent minded a Koyo branded one myself. Though cant argue with having the OEM product!

Never seen an end plate on a HT. Just a pin surrounded by a cavity and then a seal.
No identifying marks doesnt instill confidence! I wouldnt havent minded a Koyo branded one myself. Though cant argue with having the OEM product!

End plate is at the opposite end to the plunger bit.

Ohhhh I just reread your post... Totally misunderstood you there! That sounds awful :/ Never seen one like that either haha. Goodyear should stick with tyres!
Bursons water pumps are at least generally (if not always) GMB and are made in Japan. Not expensive either. Is your water pump branded?

Check out how universal the HT is! http://www.ebay.com.au/itm/95-09-2-5L-3-0L-3-5L-3-8L-CHRYSLER-DODGE-MITSUBISHI-HYDRAULIC-TENSIONER-ADJUSTER-/160881678743?pt=Motors_Car_Truck_Parts_Accessories&hash=item25754b9997

So max, I assume that link os USA. Why not just get genuine one? I really struggle sometimes at the attitude from some where they just have to save $5 with no concern of the consequence

Originally ntn were cast iron body yhen went to alloy with end cap now no end cap. Others such as the 6A1x series are still cast iron body