5ME experts please read

[triver525]

Please check out this thread. I am having troubles with my 5ME timing chain.

1982 Cressida Timing Chain Issues

[Doctor J]

This problem is also common on 4ME engine, in fact on my 79 Supra the chain was also loose for 12 years and some "expert" mechanics promised to me that it will fell off in a month.
When I desided to carry out the head gasket replacement (I am not a certified engine specialist), I removed the tensioner plunger from the head and noticed that it was stuck midway, so it was just holding a chain, instead of applying tension to it.Weak tensioner had also caused wear on the tension roller, however, even if it loses all plastic/rubber teeth nothing will happen.
This is what you can do to check the tensioner:

• Remove power steering pump belt
• tilt the pump toward engine
• place 17mm deep socket on the hex on the tensioner body,
• using suitable drive, unscrew tensioner assembly, do not lose fiber washer between tensioner and the head.CAUTION: do not rotate engine when tensioner is removed.
• now, inspect the tensioner: the 10 mm diameter spring loaded plunger must extend under spring force up to 50 mm, if exposed end is shorter, replace the tensioner.
• Installation is in reverse order; torque tensioner to 30 ft x lb, adjust 8mm slotted screw according to the manual.

Hope this helps.

[triver525]

So I pulled out the tensioner this morning and I found that it isn't actually holding tension on the chain. I could push the plunger back in even when it was still in the car. I assume this is a hydraulic unit. I didn't notice any oil lines going to it though. It appears that this unit was only pressing on the chain with spring pressure.

How does the tensioner work and should I just be replacing it? Are there mechanical tensioners available? Oh, and what does the screw adjustment do?

I can also see the all the rubber teeth of the idler sprocket are worn off. Should I be replacing?

[Doctor J]

There are two springs inside: one big, another small. Worn out teeth on the tensioner roller are not a problem (many cars were able to go more then 70000 mi after wear was discovered and chain never failled).
When the tensioner is off the car, how far the plunger (10 mm dia rod) is sticking out?
Tensioner is mechanical, spring loaded, the circular gap between the threads on the body is to collect oil for lubrication, not for hydraulic pressure.
This is how to adjust the tensioner:

• loosen 12 mm lock nut
• turn the adjustment screw with the flat screwdriver clockwise until resistance felt
• back up screw one full turn
• tighten locknut

Usually, if screw cannot be rotated, the tensioner requires replacement. In most cases the screw threads protrude about 2 to 4 mm above lock nut.

Replacement of the chain set is possible with the head on the car, but this procedure may tear off the front portion of a head gasket and pan gasket as well.

[triver525]

Thank you very much for your help. The plunger sticks out about 1.5". I can press it in reasonably easily and it'll pop back out. It feels a little sticky though. I tried tightening the adjuster screw but it didn't seem to do anything. The plunger still travels back completely into the housing.

EDIT: I just went out and did some actual measurements. The plunger extends 30mm out of the tensioner body. The adjustment screw does adjust the plunger out somewhat but I don't know if it is enough or not.

[Doctor J]

The adjustment screw just compresses the small spring, which actually makes only a fine adjustment. As far as I remember, the almost new plunger was sticking out very close to 2 inches. The best idea is to compare the spring effort/ plunger exposed lenght of one that you have to the new one.