Gasoline-Engine Camshaft Wear: The Culprit is Blow
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Originally Posted By: Linctex
The surface of a lifter is slightly convex.
It rotates as it "rolls in a circular pattern" over a cam lobe.
Yes, lots of rotating followers out there, but they are certainly not universal in ohv valve trains. The British Twins used a block follower, although the AMC twins used a roller. These are Triumph followers, high performance versions used a flatter radius...BSA and Norton were similar. I used to see plenty of wear in these things, but never totally destroyed, I guess the useless oil of the day was ok in this application. Some of the worst wear I've ever seen in pushrod camshafts was with early VW engines...the lobes would be pear shaped.
I'd go along with blow by and camshaft wear...but in engines with excessive blow by, camshafts were down the list of things worn out.
The surface of a lifter is slightly convex.
It rotates as it "rolls in a circular pattern" over a cam lobe.
Yes, lots of rotating followers out there, but they are certainly not universal in ohv valve trains. The British Twins used a block follower, although the AMC twins used a roller. These are Triumph followers, high performance versions used a flatter radius...BSA and Norton were similar. I used to see plenty of wear in these things, but never totally destroyed, I guess the useless oil of the day was ok in this application. Some of the worst wear I've ever seen in pushrod camshafts was with early VW engines...the lobes would be pear shaped.
I'd go along with blow by and camshaft wear...but in engines with excessive blow by, camshafts were down the list of things worn out.
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That's a 2.0 Cortina head I think - cast iron and cross flow, Nissan and the Mercedes they coppied were alloy and had both manifolds on the same side. This is a KA24, but certainly no flat tappets here. Side trackers...grrrr.
Ummm, can't seem to post an image to night.
Ummm, can't seem to post an image to night.
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The 2.0 "Pinto" engine was the one that went into everything (Oz Escort RS2000), and up to 2.3 in American Mustangs and Fairlaines IIRC ??? LOL.
Vizard has a great book on them (funny, another RAT reference right there)
That was one in the initial paper, that I found through chasing down the Sequence IVA, which is with a Nissan engine of apparent predictable vulnerability in the cam area.
Vizard has a great book on them (funny, another RAT reference right there)
That was one in the initial paper, that I found through chasing down the Sequence IVA, which is with a Nissan engine of apparent predictable vulnerability in the cam area.
Originally Posted By: Shannow
Not a great deal of rotation in the 2.3 OHC engine in the study
Yes - BUT LOOK at how WIDE the lobes are!!
Now go look at the (respective) narrow lobes on a Chevy 350
The increased surface area makes up for the non-rotating design
Not a great deal of rotation in the 2.3 OHC engine in the study
Yes - BUT LOOK at how WIDE the lobes are!!
Now go look at the (respective) narrow lobes on a Chevy 350
The increased surface area makes up for the non-rotating design
I don't know why it's called the Pinto, it was a German engine and we saw it in 1600 and 2.0 versions in English Fords. I guess the extra weight and emission controls for the US killed the power so they got a 2.3 version. They gave a lot of cam trouble - clack, clack, clack. You could buy a new cam and finger followers pretty cheap, but you had to remove the head to get the cam out, so not many people took that option. Us dodgy mechanics would find the noisy one and just replace the followers that were noisy. They had an external oil feed line bolted to the pedestals that used to break. So the wide lobes didn't stop wear.
We had a guy with a MKIII Cortina on the island , as he drove by on the forecourt it would be going clack, clack , clack. I bought it, thinking I was just going to replace a follower to get a nice runner. Not to be, it had a collapsed piston. Duh.
We had a guy with a MKIII Cortina on the island , as he drove by on the forecourt it would be going clack, clack , clack. I bought it, thinking I was just going to replace a follower to get a nice runner. Not to be, it had a collapsed piston. Duh.
Originally Posted By: Silk
... They gave a lot of cam trouble - clack, clack, clack. You could buy a new cam and finger followers pretty cheap, but you had to remove the head to get the cam out, so not many people took that option. Us dodgy mechanics would find the noisy one and just replace the followers that were noisy. They had an external oil feed line bolted to the pedestals that used to break. So the wide lobes didn't stop wear.
Yes those Pinto engines were notorious in the UK for cam failure. I distinctly remember witnessing a rebuilt engine being cranked while oil was poured on the camshaft lobs. It took an age for the oil to come through the oil feed line. That research project may have deliberately picked an engine known to be hard on it's cams.
... They gave a lot of cam trouble - clack, clack, clack. You could buy a new cam and finger followers pretty cheap, but you had to remove the head to get the cam out, so not many people took that option. Us dodgy mechanics would find the noisy one and just replace the followers that were noisy. They had an external oil feed line bolted to the pedestals that used to break. So the wide lobes didn't stop wear.
Yes those Pinto engines were notorious in the UK for cam failure. I distinctly remember witnessing a rebuilt engine being cranked while oil was poured on the camshaft lobs. It took an age for the oil to come through the oil feed line. That research project may have deliberately picked an engine known to be hard on it's cams.
Anyway, that's not the engine they were testing, this is a KA24 cyl head. Not that common in NZ, and I've not had much to do with them.
Originally Posted By: Silk
Anyway, that's not the engine they were testing, this is a KA24 cyl head. Not that common in NZ, and I've not had much to do with them.
No, the one in the blowby test paper was the 2.3 pinto...they used it in just about every lube related test back in the day. Being common, they ised them for cold flow studies, camshaft temperature studies, economy comparison studies the lot.
the Nissan 2.4 engine is the one that they use for the Sequence IVA test.
Anyway, that's not the engine they were testing, this is a KA24 cyl head. Not that common in NZ, and I've not had much to do with them.
No, the one in the blowby test paper was the 2.3 pinto...they used it in just about every lube related test back in the day. Being common, they ised them for cold flow studies, camshaft temperature studies, economy comparison studies the lot.
the Nissan 2.4 engine is the one that they use for the Sequence IVA test.
Ah, I only read the top link where they mentioned the KA24, the other links looked like they wanted me to pay, so didn't go there. The old Cortina engine (we never got the Pinto, so it's not a Pinto engine to me) certainly had cam problems, but they weren't the normal pitting of lobes and followers you get with pushrod engines. The lobe would wear at an angle, and the clacking was the finger follower flicking off to the side. Then a fractured oil pipe which squirted oil onto the lobes wouldn't help...the 2 were separate problems, you didn't need a broken pipe to get a clacking follower, and a broken pipe didn't mean the cam or followers were going to be a problem.
The Mitsubishi 4D56 had similar problems, they would come in with a cyl out going duh, duh, duh out the intake. The roller on the rocker would be collapsed, but the wasn't the whole problem. The rocker shaft would wear, this put the rocker at an angle, loading the roller, and the angled roller would wear into the cam. You could replace individual components, but the real fix was rocker shaft, camshaft and rockers. Could be an oil related problem, as I haven't seen one do that for a decade, and they are still around...but the oil is better.
The Mitsubishi 4D56 had similar problems, they would come in with a cyl out going duh, duh, duh out the intake. The roller on the rocker would be collapsed, but the wasn't the whole problem. The rocker shaft would wear, this put the rocker at an angle, loading the roller, and the angled roller would wear into the cam. You could replace individual components, but the real fix was rocker shaft, camshaft and rockers. Could be an oil related problem, as I haven't seen one do that for a decade, and they are still around...but the oil is better.
Silk,
do you know what the lifter/cam thing was on the 2.0 Captiva diesels ?
Wife's car just got a recall done (160,000km on it) where they did the cam and rockers, and all the FI pipework that they had to pull off to get to it (threw in a timing belt too).
do you know what the lifter/cam thing was on the 2.0 Captiva diesels ?
Wife's car just got a recall done (160,000km on it) where they did the cam and rockers, and all the FI pipework that they had to pull off to get to it (threw in a timing belt too).
I've heard it's a rocker bush failure, but I've never come across any one who has had the problem, or someone who has done the fix. Dealer only fix, we have ex Nissan and Toyota mechanics in the company, but no one who has worked for GM to give us the low down.
Yeah,
Holden had it for a day to do the rockers, pulled the covers off and said that it had spread to the cam...come back in a fortnight for 2 days in the shop.
The recall mentioned something about "wear with poor quality used oil" or some waffle.
Holden had it for a day to do the rockers, pulled the covers off and said that it had spread to the cam...come back in a fortnight for 2 days in the shop.
The recall mentioned something about "wear with poor quality used oil" or some waffle.
They probably had a bunch of V6 Commodore timing chain jobs to get out of the way first. Dealer servicing and poor quality oil ? I look at any engine from the '60's, and wonder what engineers have learned in 50 years, not a lot apparently, reliability is going backwards not forwards. With over 100 years experience and the quality of present day engineering, we should be buying one car for life, and it should last that long.
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Originally Posted By: Chris142
I have lost a cam in a 350 Chevy.
I think everyone who had a 350 Chevy lost a cam.
I have lost a cam in a 350 Chevy.
I think everyone who had a 350 Chevy lost a cam.
MolaKule
Staff member
BTW, Tribology and Lubrication Technology (TLT) has an excellent article in the February issue called, "Examination of the Axial Shape of the Automotive Valvetrain Cam for Engine Friction Reduction," Page 52.
Originally Posted By: Silk
They probably had a bunch of V6 Commodore timing chain jobs to get out of the way first. Dealer servicing and poor quality oil ? I look at any engine from the '60's, and wonder what engineers have learned in 50 years, not a lot apparently, reliability is going backwards not forwards. With over 100 years experience and the quality of present day engineering, we should be buying one car for life, and it should last that long.
The manufactures want to sell new vehicles. They are cad cam engineered to perfection. Nothing extra left on the table.
They probably had a bunch of V6 Commodore timing chain jobs to get out of the way first. Dealer servicing and poor quality oil ? I look at any engine from the '60's, and wonder what engineers have learned in 50 years, not a lot apparently, reliability is going backwards not forwards. With over 100 years experience and the quality of present day engineering, we should be buying one car for life, and it should last that long.
The manufactures want to sell new vehicles. They are cad cam engineered to perfection. Nothing extra left on the table.
The 350 engines in my 1974 Chevy Monte Carlo and 1979 Chevy 3/4 Ton 4x4 had absolutely no problem grinding down their camshafts in under 50,000 miles. The local auto parts shop that we bought parts from, when I was working at a Gas Station, had GM camshafts on hand on the shelves. No need to order.
I don't recall huge problems in the earlier ones; 1974 might have been not bad. 1979 would have been pushing it, and I have replaced them in small blocks of that vintage, prematurely, too.
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