I own a 1999 ford taurus with a 3.0 l 24 valve dual over head cam v6 . I’ve recently experienced a knock that has been diagnosed as a lifter or rocker arm , when valve covers and manifold were removed rocker arms seemed fine so I would assume lifter, but as I was recently told cars with over head cams run on cam followers not lifters , is that true?
Lifters are cam followers, but with overhead cams, sometimes the rocker is the cam follower. Hydraulic lifters can be built into the lifter or in the case of some Ford engines, the lifter is actually built into the head, the rocker hinges on the lifter at one end and the cam pushes down on the center of the rocker. I don’t think anyone else uses that setup but Ford.
Many manuals will explain what you are looking at. They might tell you where to check for wear. What parts were identified in the manual? Just looking at them may not be enough without checking the clearance.
Thanks Keith much appreciated, pleasedodgeevan baught it threw 3rd party and no manual with it
The primary function of the device in question is to provide a low-resistance surface for the cam lobe to follow and/or to take up the space in the mechanical train that goes from the camshaft to the valve stem to allow proper adjustment. Its location can be in a few different places with an overhead cam engine. One arrangement has the camshaft pushing up the rocker arm that them pushes down on the valvestem. The device can be either between the can lobe and the rocker arm or between the rocker arm and the valve stem. Another arrangement has the rocker arm funcrum at the end of the rocker arm and the cam lobe pushes down on the center of the rocker arm, which then pushes down on the valvestem. The device on that arrangement will typically be between the valve stem and the rocker arm’s reciprocating end. A cam shaft lobe can even push directly down onto a valve stem, and in that arrangement the device is between the lobe and the valve stem.
I never liked the term “tappet” and its sister term “lifter”. I understand that if the device is being pushed downward instead of upward, “lifter” seems somehow inappropriate, but I always felt that focusing on exact nomenclatures just confused things. “Cam follower” is just another term. It’s more important to understand how the valve train works than to get the terms exact all the time. Besides, different manufacturers will often use different terms for exactly the same part. One manufacturer’s “garnish” is another’s “trim”.
For the record, radial aircraft engines will adjust that dimension using varying pushrod lengths. One does the assembly using a shorter pushrod, measures the “play”, and selects the appropriate pushrod length in accordance with a chart. Perhaps since some “lifters” are being pushed up, some sideways, and some down, “cam follower” is a better term than “lifter”.
be very careful with this one! I have the exact and car, and noise! sounded like the engine was about to go. I found out it was the A/C compressor! The shaft bearing was toast and making it rattle. sounded exactly like a rod knocking.I didn’t anything else (like you did),but turned the a/c on one hot day, and the sound stopped! Turned out off, and it was back instantly. I was about to pay for a rebuild until the accidental find! Also amazingly, my father in-law had the exact issue with his 03 Taurus. knocking compressor! Turn your a/c on and off first!
also this car has no lifters. the camshafts directly drive the rocker arms.
I’m guessing then that the lash is adjusted at the cam lobe end of the rocker via the cam follower?
Or is the adjustment at the valve stem end and the cam follower a fixed dimension part?
I wish I still had access to Mitchells.
I believe I read these are hydrolic lash adjusters. I did read for sure that they are meant to never need adjustment,so that should mean it is hydrolic.
Those small lash adjusters are used on many types of engines and not just Fords. Failure of the adjusters is usually due to sticking or disentegration of the hardened adjuster tips; either from miles or an extended oil change regimen.
I wish I still had access to Mitchells.
TSB:
A few years ago I noticed our library had several shelves of Mitchell Repair manuals. Check to see if yours does as well.
I also noticed our library, (and hence the libraries in neighboring towns via their network), had access to numerous online “paid” databases. You got me curious as I’m going to look to see if they have access to AllData and Mitchells online systems.
Lifters or followers, no difference. This describes the part the follows the cam profiles and makes the valves open, sometimes WITH a rocker arm and sometimes directly on the valve.
This must be the 3.0 L Duratec engine with rocker arms. There was a version of this engine in Lincolns and Jaguars that had the cams acting directly on the valve. Leave it to Ford to proliferate version of a single engine design!
That’s a good suggestion, Joe. I’ll have to check that out. Before I retired from the college I also had a link directly into Toyota’s documents. I never really knew how I stumbled into that, it was by accident, but that’s lost to me too. It may have been because one of our sister campuses has a contract with Toyota to teach a Toyota sponsored, Toyota-specific program.