used on PSA diesel engines. piston to valve contact supposedly breaks the interference fit of and the engine stalls, mitigating damage.
cool stuff. skip to 13 minutes
cool stuff. skip to 13 minutes
press fit cam lobes
- Thread starter 2EHA
- Start date
Interesting, wonder if this is the reason that VW uses these on the EA211.
Interesting. Would require the valves to be perfectly perpendicular to the cylinder, right? with a flat piston under it, well under most of the valve, so as to avoid pushing sideways on the valve.
Not a bad idea. If it all goes bad, then it's just a tow & a new cam added to the timing belt job. As opposed to a refurbished head.
Not a bad idea. If it all goes bad, then it's just a tow & a new cam added to the timing belt job. As opposed to a refurbished head.
VW has been using hyrdoformed press fit cam lobes for many years. Unfortunately when the timing chain tensioner fails and the engine jumps time, not only do they bend valves, they shift the lobes on the cams. Makes for a very very expensive repair.
Humble Mechanic just did a tear down video on this. 1.4 L that jumped time, had to replace the whole head.
Volvo trucks are using press fit lobes with a fair amount of trouble. I believe Paccar may be using them now but I'm not sure. The Volvo engines like to spin lobes.
Didn't the Yamaha V8 used in the Taurus SHO have problems with the cam lobes walking out of position?
The SHO Yamaha was a V6.
Sounds like a solution looking for a problem
the jellybean had a V8. made out of an extended duratec block and their own heads. cam sprocket liked to break off
I should have known that! Only 3.4 l, if I recall correctly - pretty small for a V8. (Edit: Wiki says the Yamaha engines were 3.0 and 3.2 l. There was a 3.4 l V8 later, not a Yamaha.)
The late 90s Taurus SHO was a V8. Machining was finished by Yamaha. The problems it has was that the cam sprocket was press-fit to the cam. It eventually would work loose and destroy all kinds of parts. The fix was to weld the sprocket to the camshaft.
UVVT - Unintentional Variable Valve Timing. Oops!
So they forego setting up machinery to cast and dress the lobes on a solid camshaft in favor of "add on lobes".
But then they don't secure them? How lame is that?
But then they don't secure them? How lame is that?
Pressed on cam lobes has got to be the most shameful use of press fit I've ever seen. Bearings, sure - but Cam Lobes?
No way does that make sense to me. Absolute proof bean counting has gone too far.
The potential damage to an engine and the lost time for a sole proprietor when his work van is down is not fair at all.
This is cost shifting to the consumer without knowledge/true consent of the buyer on what they are getting.
Looks like it was Honda that came up with this as best I can find:
I would have thought Honda would have done better engineering than this. The patent explains this is to reduce manufacturing steps and therefore cost - "the present invention to provide a camshaft, which can be manufactured in a reduced number of manufacturing steps enabling higher productivity." In this case, higher productivity means more cams made per hour, hence, lower cost per unit. I doubt the car pricing was lowered to match the savings so the cost shift was really passed on in the form of higher maintenance costs down the road to the purchaser.
This was eye opening for me. I will do my best to avoid engines with this type of camshaft. Same way I am avoiding the FIAT diesel engine in RAM trucks because of it's pressed on cam sprocket and it's failure right after the warranty is expired.
And I thought the only Cam issues were SADI versus Billet. Thanks for posting this!
No way does that make sense to me. Absolute proof bean counting has gone too far.
The potential damage to an engine and the lost time for a sole proprietor when his work van is down is not fair at all.
This is cost shifting to the consumer without knowledge/true consent of the buyer on what they are getting.
Looks like it was Honda that came up with this as best I can find:
US7628129B2 - Camshaft, method of manufacturing cam for camshaft, and method of manufacturing shaft for camshaft - Google Patents
A method of manufacturing a cam for a camshaft, comprising the steps of continuously applying, to a billet having a volume larger by a specified volume than a final product, a plurality of cold forging steps formed of a preliminary outline upsetting, an outline drawing, a simultaneous piercing...
patents.google.com
I would have thought Honda would have done better engineering than this. The patent explains this is to reduce manufacturing steps and therefore cost - "the present invention to provide a camshaft, which can be manufactured in a reduced number of manufacturing steps enabling higher productivity." In this case, higher productivity means more cams made per hour, hence, lower cost per unit. I doubt the car pricing was lowered to match the savings so the cost shift was really passed on in the form of higher maintenance costs down the road to the purchaser.
This was eye opening for me. I will do my best to avoid engines with this type of camshaft. Same way I am avoiding the FIAT diesel engine in RAM trucks because of it's pressed on cam sprocket and it's failure right after the warranty is expired.
And I thought the only Cam issues were SADI versus Billet. Thanks for posting this!
Last edited:
