Change the timing chain tensioner the easy way

[tjts1]

Reading through the various methods and debates out there about changing the timing chain tensioner, most call for installing the tensioner compressed as it comes out of the box, then once installed rev the engine to 3500 rpm and cross your fingers the loose chain will slap the chain rail against the tensioner to release it before the chain jumps a tooth or 3. The whole reasoning behind this method is that you won't be able to install the chain tensioner once its extended. I don't know how this idea got started but I think its WRONG. Here's my simplified method.

1. Remove the old tensioner via the 19mm bolt on the passenger side of the engine. Once out it will look like this. Old extended tensioner is on the right, M44 style compressed tensioner on the left.
http://farm2.static.flickr.com/1325/533484828_cd4127e2f1_o.jpg

2. De compress the new tensioner by pressing the ends down against the table with your hand and twist about 1/4 turn. It will pop out and look like this.
http://farm2.static.flickr.com/1108/533584601_5ec4defc88_o.jpg
As you can see fully extended the new tensioner is slightly longer than the old tensioner. This is due to wear on the old tensioner spring and part of the reason why it needs to be replaced.

3. Install the new tensioner the same way the old one came out. When you reach the point where you need to thread the cap back in, apply pressure to the tensioner. My guess is that it takes about 20 lb of pressure to compress the spring with one hand on the head of the cap. Its not that hard to compress. The cap can then be tightened by hand when the threads catch.
http://farm2.static.flickr.com/1098/533484882_2444eac0a6_o.jpg

4. Tighten the cap with a 19mm wrench to torque spec. Since I don't have a torque wrench just used my own estimate. Remember that the threads are in aluminum so don't over do it. Think of of it as an oil drain plug. I removed the valve cover to paint it as well as inspect the timing chain gears but its not necessary. In the red circle you can see the head of the new tensioner fully extended.
http://farm2.static.flickr.com/1379/533500012_0292dc5e5e_o.jpg

5. Once everything is buttoned up, start the engine and let it idle. You will get a very loud chain noise for a split second until oil pressure reaches the tensioner, then it will get quiet all of a sudden. You don't have to rev the engine. Just let it idle for a minute or so. It should give you time to check for oil leaks from the tensioner bolt.

Remember that this isn't the only way to replace the tensioner. The 2 articles below outline a different method that has been proven to work effectively many times over. I'm just offering another alternative that worked for me.
http://www.bmwe30.net/cgi-bin/datacgi/database.cgi?file=articles&report=view&ID=00072&Section=08

http://www.esatclear.ie/~bpurcell/318isfaults.html#timingchaintensioner

[RED IS 91]

great info and a great how-to .
Unfortunately for me I just replaced my tensioner .I did the cross my fingers and rev to 3500 method.
Everthing worked out but still a tense moment.

[kowalski]

i did it by installing it decompressed with no problems as well. Seemed like the sensible thing to do to me.

[Vladi]

Does anyone know when should we change parts 17, 8 and 10?
http://www.realoem.com/bmw/showparts.do?model=BE51&mospid=47425&btnr=11_1370&hg=11&fg=25

[tjts1]

Does anyone know when should we change parts 17, 8 and 10?
http://www.realoem.com/bmw/showparts.do?model=BE51&mospid=47425&btnr=11_1370&hg=11&fg=25
A lot of info on the subject here.
http://www.esatclear.ie/~bpurcell/318ismaintenance.html#timingchain
Good luck.

By the way, I was born in Bucuresti. I speak some Romanian but writing is a bit tougher. Moved to the US in 1990.

[sheepdog]

Does anyone know when should we change parts 17, 8 and 10?
http://www.realoem.com/bmw/showparts.do?model=BE51&mospid=47425&btnr=11_1370&hg=11&fg=25

If the tensioner is kept in check, the guides will go for a VERY long time. Much longer than 100k, but only if the tensioner is not allowed to wear out.

Cheap insurance is replacing the tensioner every 40k.

To my knowledge, none of this has an official service interval.

[Eurospec]

A lot of info on the subject here.
http://www.esatclear.ie/~bpurcell/318ismaintenance.html#timingchain
Good luck.

By the way, I was born in Bucuresti. I speak some Romanian but writing is a bit tougher. Moved to the US in 1990.Holy crap.... another Romo in the house. What are the odds of this. LOL

[Vladi]

A lot of info on the subject here.
http://www.esatclear.ie/~bpurcell/318ismaintenance.html#timingchain (http://www.esatclear.ie/%7Ebpurcell/318ismaintenance.html#timingchain)
Good luck.

By the way, I was born in Bucuresti. I speak some Romanian but writing is a bit tougher. Moved to the US in 1990.

Glad to know it! :D

Holy crap.... another Romo in the house. What are the odds of this. LOL
Dude, there's something fishy going' on here. :D

[Asserti]

So this is the best/safest/ most recommended way to replace the chain tensioner?

I'm going to do mine in a few weeks.

[sheepdog]

So this is the best/safest/ most recommended way to replace the chain tensioner?

I'm going to do mine in a few weeks.

Ignore pulling the cover.
Instead, pop the new tensioner prior to install.
It makes it only a little more difficult (easy job still) and ensures no problems.

Takes 5 minutes to change it this way.

[Asserti]

Thank you very much!

I still think this is one of the best boards I've ever registred. I'm sorry that I'm not more active here, have some other boards that take allready a lot of my time.

Keep up the good work though!

[Nomadic]

I did it this easy way and it worked like a charm. (decompressing the tensioner first and applying pressure to 19mm cap to thread to install ) There still was some brief slapping while the tensioner was filling up with oil and coming up to pressure, but worked well.

Thanks for the post!

[e30 4cyl]

Thanks for the writeup, I will need to do this eventually.

[bmwpower]

+1

Did this when I fired up my engine for the first time the other day. Does make a lot of noise for maybe 5-6 seconds and then you're good to go.

[keflaman]

Worked like a charm. My chain noise disappeared almost instantly and I can't believe how much smoother and quieter the motor is.

[mgold]

Would it make sense to soak the tensioner in fresh motor oil before installing it?

[bmwpower]

Would it make sense to soak the tensioner in fresh motor oil before installing it?

Possibly. My guess is it will just squeeze out until the oil coming from the engine gets to it. Not sure how much is compresses upon startup though.

[Asserti]

Would it make sense to soak the tensioner in fresh motor oil before installing it?

It will be more difficult to install it, because the oil wil prevent the tensioner to be pressed in. Because you need to press it in when installing, I wouldn't do it.

You can try to reinstall your old tensioner first, that will still be full of oil and you will note that it'll be hard to press in.

[josephb983]

As you can see fully extended the new tensioner is slightly longer than the old tensioner. This is due to wear on the old tensioner spring and part of the reason why it needs to be replaced.

Actually, it is longer because the new tensioners use a different design. If you dismantle the new tensioner it uses a longer narrower spring, with more coils. EDIT: Do not dismantle the new tensioners, they can be very difficult to reassemble. The old tensioner uses a larger shorter stiff spring. I think the new design is meant to be more durable, as the spring is a lot longer, and coiled smaller on each end. If you check the old tensioners, they are fully extended when they are 1/8 shorter. The best way to test the old tensioner is to try to compress it with your hands. Then compress the new tensioner with your hands. If they require about the same pressure your tensioner is probably fine. If the old one is easy to compress, you need a new tensioner.

Also, the old tensioners could get stuck fully extended, which was dangerous to the timing chain. The new design does not stick extended, that I could see. I tried every which way to get it to stick, and it just plain wont. The Haynes manual warns of the dangers of installing a tensioner extended, as the old design would lock extended easily.

I took out the new tensioner, after running the engine, to make sure it was full of oil, and it was. There is no reason not to use the approach described in this article, installing the tensioner extended. The rev to 3500 rpm approach is dangerous for the engine, for no purpose. Use a prybar and hold the tensioner in while you tighten it. I did this prying off of my windshield washer tank, and it didn't hardly bend the plastic. It doesn't take much pressure on the 19mm cap to hold the tensioner in place, once forced in (I forced it in by hand before prying on it).

Just thought I'd post this, as I've seen reference to this 1/8 inch difference several times as if it implied a failed tensioner. The old ones were designed 1/8 inch shorter. (Note that I didn't actually measure it, 1/8 inch is just eyeball measurement).

[josephb983]

One other note, be very careful when popping out the new tensioner. When I did it the parts went flying everywhere, and it took me 2 hours to get the dang thing back together.

I suggest holding the ends of the new tensioner tightly, while turning to get it to pop out. It only takes about 20lbs of pressure to keep it compressed I think.

Good luck.

[quinn11m20]

I just changed my tensioner and my car sounded like a deisel for on or about 1 and a half, then it quietened down and I still kind of hear chain rolling. Am I supposed to here the chain?

[quinn11m20]

correction a minute and a half

[E-30Dubbsz]

I just changed my tensioner and my car sounded like a deisel for on or about 1 and a half, then it quietened down and I still kind of hear chain rolling. Am I supposed to here the chain?

yeah, mine did the same thing. I am guessing that my guide rails must be worn. So, I am going to have to look at those. Also drop my oil pan to see if I have pieces in there from it.

[Asserti]

I just changed my tensioner and my car sounded like a deisel for on or about 1 and a half, then it quietened down and I still kind of hear chain rolling. Am I supposed to here the chain?

have you pushed the trotthle to 3000 rpm till it quietened down?

[e30Andym42]

yep had the same problem, used the same method, and am very happy i did so. after about 15 seconds, i held it at 3500 RPM for...maybe 3 seconds? not quite sure if it helped, but i only really hear the chain at about 2000 and even then its hardly recognizable, other than that, it's rly not noticeable at all. THANKS FOR THE TECHNIQUE :D

[PaulC]

Used this method today except I didn't pry the tensioner. Just used both hands, threaded it in and torqued it down. (the motor and engine bay are partially stripped though) Thanks to the OP for posting this.

[rhogg]

Regarding changing the tensioner - both ways work. Pushing it in decompressed is not that difficult. I oiled mine both installing.

Regarding the rails - I didn't like the noise I was hearing so I changed the tensioner. Wasn't crazy about the way the timing sprockets looked and had an oil leak so I changed the chain. Figured if I was going to take it apart I might as well have the rails just in case. The two side rails had virtually no wear, the bottom rail fell apart in my hand, and the upper rail had some wear.

The directions on the link provided above to Bredan Purcel``s page are very good. I followed them and was surprised at how well and relatively quickly it went. The engine is still noisy, but quieter and the sewing machine sound has gone. Plus no oil leaks!! :D The car is a 91 318 and has just under 120K miles.

[FL318is]

Ok, new rails and tensioner about 6 mos ago. Everything fine until recently. When I start tje car there is a ticking/tapping sound which after about a minute goes away.

Could the tensioner be "bad"? Or is it more likely the hydralifters? Is that what they are called?

[peerless]

Statement retracted. That is all.