Dispeling M96 engine rumors

[Dragonwind]

I think the biggest one for me, and despite the respect I have for Jake, is the lifters issue. At first he claimed it was robbing power, now in another post he mentions it is fuel economy and no car dyno'ed gave more than 1hp gain. My mechanic who has rebuilt many a M96 motor hasn't seen these problems. And if it were MPG then why does my 99 still get the same MPG that it was rated for 10 years ago with 89k on the OD (and I keep her in the high revs)?

Chris

[Jake Raby]

Originally Posted by Dragonwind

I think the biggest one for me, and despite the respect I have for Jake, is the lifters issue. At first he claimed it was robbing power, now in another post he mentions it is fuel economy and no car dyno'ed gave more than 1hp gain. My mechanic who has rebuilt many a M96 motor hasn't seen these problems. And if it were MPG then why does my 99 still get the same MPG that it was rated for 10 years ago with 89k on the OD (and I keep her in the high revs)?

Chris

Like I said, there are no blanket statements that can be made with these engines and their issues. Some cars that have lifter issues make much more power after they are remedied.. Others lose MPG but never really lose power, and some engines make more power from the factory than others.

It has a lot to do with how many lifters are bad and if they are on the intake or exhaust valves.

What I said was:

I recently had a car show up here with 22 of 24 lifters bad, after our work the MPG jumped up 5 MPG, but the power didn't change more than 1HP and 1.5% average torque.

Note that is ONE instance with one car. Some engines that we do this work to do pick up power, I have seen as much as 6HP and 11 lb/ft of torque but the biggest difference is the torque and HP plots and their smoothness. In a lot of instances the average power output is increased across the board, not just at peak output and the dip at the variocam changeover point is greatly reduced with the lifter upgrade.

If you have decent gas mileage and decent power don't worry about the lifters... They'll never fail and leave you on the side of the road.

[cnavarro]

Ok, the lifters might be one of those "while you are in there job," but again, sometimes it's needed. It's a known fact that the wear pads for the variocam on the pre-vane cell adjuster engines are typically worn out by 60-80k miles. So, while you are in there, it's easy enough to pull the lifters and check them while replacing the wear pads and chains. If you end up needing some new lifters, why not replace them all? Or third option, rebuild the set of lifters rather than replacing them- a cheaper third option.

I'll continue to add to the list - chain tensioners. They have been revised and updated, and again, some at even low mileage have excess clatter at startup that may be a lifter or lifters or the chain tensioners. Retail, they are not even that expensive. We reused a set of low mileage tensioners on my 2.9 and even with an accusump pre-oiling the engine, I can hear them. So this winter, they are getting swapped out for new ones. Lifters were new since all of them were bad on the low mileage donor.

This isn't a problem isolated to the M96. Our W8 Passat with 55,000 miles has it's engine out for failed chain tensioners, thankfully under powertrain warranty since it's an 8-10k repair!. Makes the M96 look downright inexpensive to repair!

Unfortunately, frequent oil changes alone aren't a cure for lifters and tensioners. Hell, my W8 had it's oil changes every 5,000 miles (10L fill, half the factory drain interval) with Motul every fill and the tensioners still failed.

We just have to learn to deal with what we are given and work within those constraints.

[Dragonwind]

Originally Posted by Jake Raby

If you have decent gas mileage and decent power don't worry about the lifters... They'll never fail and leave you on the side of the road.

Thanks Jake and fair enough. I'll deal with them in a few years when it is valve job time. Maybe by then I'll drop in one of yours.
Chris