Found Bad tappets; but cam looks and feels perfect. What should I do? : MGB & GT Forum : The MG Experience

Found Bad tappets; but cam looks and feels perfect. What should I do? #1
JuancarlosMGB Juan Carlos Perez Velasquez Madrid, Madrid, Spain Sign in to contact 1974 MG MGB GT "El Cherada" 1978 MG MGB Racecar "El 81 De Carrera" 1995 Honda Civic "Beasty Boy (Race Car)" 1999 BMW Z3 Coupe "BATMOBILE"	Topic Creator (OP) Mar 31, 2015 12:23 PM Joined 16 years ago 1,580 Posts

Last weekend I posted a topic where I attached a video about an annoying knocking from my engine. After checking almost everything, I found two bad lifters: #4 and #5.
I started to remove the camshat in order to inspect the lobes; but they look and feel smooth, just like new.
What should I do: Should I just replace the lifters? What could be the possible reason for the lifters fail?

I am attaching the video where you could listen to the noise; and a picture of one of the dmaged lifters.

Disclaimer: Race engine. The cam is a Delta D9 with about 60 working hours. Lifters where replaced with the cam about one year ago.

Edited 2 time(s). Last edit at 2015-03-31 12:57 PM by JuancarlosMGB.

IMG-20150331-01559.jpg 31.8 KB

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #2
brasil Juergen K Duesseldorf, Germany Sign in to contact 1966 MG MGB	Mar 31, 2015 12:31 PM Joined 11 years ago 151 Posts

Hello Juan Carlos

if it were my engine.... new cam new lifters.

What type of engine oil did you use ? I am asking, because the "NEWERSTUFF" doesn´t carry enough ZINK ( ZDDP )

Greetings Jurgen

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #3
JuancarlosMGB Juan Carlos Perez Velasquez Madrid, Madrid, Spain Sign in to contact 1974 MG MGB GT "El Cherada" 1978 MG MGB Racecar "El 81 De Carrera" 1995 Honda Civic "Beasty Boy (Race Car)" 1999 BMW Z3 Coupe "BATMOBILE"	Topic Creator (OP) Mar 31, 2015 12:41 PM Joined 16 years ago 1,580 Posts

I used Kendall GT1 for the first (and Last) time. I forgot to check the ZDDP percentage. My bad!

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #4
Steve64B Steve Opitz Phoenix, AZ, USA Sign in to contact 1966 MG MGB	Mar 31, 2015 12:44 PM Top Contributor Joined 17 years ago 11,646 Posts

If you replace just the lifters... replace ALL the lifters! Also, get hardened lifters like these:

http://www.aptfast.com/showitem.aspx?id=100033&name=APT%20Designed%20A%20%26%20B%20Series%20Super%20Duty%20Cam%20Followers&;

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #5
davester Dave Diamond Berkeley, California, USA Sign in to contact 1965 Austin-Healey Sprite 1971 MG MGB GT "Dad's Car"	Mar 31, 2015 12:44 PM Joined 13 years ago 2,204 Posts

I replaced my cam after measurement of the lift indicated a couple of bad lobes. The lifters looked trashed but the lobes looked nice and smooth despite being trashed. You need to measure lobe lift (get a cheapo dial indicator with magnetic base from amazon or harbor freight) to determine how bad the cam is. With ugly lifters like that I'm guessing it's bad.

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #6
HiPowerShooter James Booker Lake Winneconne, WI, USA Sign in to contact 1973 MG MGB	Mar 31, 2015 12:55 PM Joined 9 years ago 7,787 Posts

I found the same thing in my engine last year. Toasted tappets...but the cam was good. I simply replaced the tappets, used some Gibbs racing assembly lube on them and broke them in @2k RPM for 20 min. Car runs just fine. Some here will tell you that the cam needs to be replaced regardless...but that's not necessarily the case.

"One test is worth a thousand expert opinions"--Alvin "Tex" Johnston...Boeing test pilot.

"Who do you think you are? I am."...Pete Weber

73 MGB. Tires: Round, black, hold air. Oil: Sometimes old, sometimes new...always slippery. Oil filter: Yellow, usually full of oil. Carbs: 2 SU HIF. Distributor: Yes. Headlights: Not that bright but bright enough. A bunch of other stuff most cars have but not really important enough to itemize. Oh, wait...it has a cool sounding exhaust with stickers on the chrome tips. Really slays the ladies...

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #7
dipstick Kenny Snyder (RIP) La Center, WA, USA Sign in to contact 1941 Ford N-Series 1958 MG MGA 1500 Coupe "Rosie" 1970 MG MGB GT "Pat's GT" 1971 MG MGB "Gifted To Me" & more	Mar 31, 2015 01:07 PM Top Contributor Joined 15 years ago 7,564 Posts

Hi Juan,
- The pictured lifter is clearly failing, the hard surfacing is flaking away.
- #4 & #5 are exhaust lifters; I am wondering if those exhaust valves are making slight contact at full lift with the block surface and/or the pistons? I think I recall that the cylinder head was recently resurfaced which brings the exhaust valves closer to the block. With a dial indicator on the valve spring retainer, zero lash, bring the exhaust valve to full lift, with a pry bar (big screwdriver) on the retainer and push the valve down until it contacts either the block or piston and make note of the dial indicator movement. Ad the recommended lash to that number; there should be .080" clearance. Some folks use .060" clearance depending on valve weight and/or spring pressure.
- FWIW I have successfully installed new lifters on used camshafts, I don't want to get into a big discussion about this procedure.

Be safe out there.
Kenny

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #8
mvheim Mark Heim CA, USA Sign in to contact 1966 MG MGB "Uroboros"	Mar 31, 2015 01:17 PM Top Contributor Joined 18 years ago 1,927 Posts

Hmm, this happened to me a few years ago. Lifters were bad, cam looked reasonable. But when I checked the lift on the cam, it was well below spec. The lobes were seriously worn. Replaced both, and started using Mobil1 15w50 synthetic -- this particular weight of Mobil1 is designed specifically for older cars with flat tappets, with high levels of ZDDP. There are other options, but this is available locally at the same price as other synthetics.

Max Heim
'66 MGB "Uroboros"

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #9
ingoldsb Terry Ingoldsby Calgary, AB, Canada Sign in to contact 1971 MG MGB	Mar 31, 2015 01:42 PM Top Contributor Joined 20 years ago 20,149 Posts

I think the answer to your question is, how much do you want full performance and life from your engine? Some people are more than happy with a car that runs reasonably well, and they drive the car so occasionally that lifespan isn't an issue. Others want the engine to run the best it can and last as long as possible. If you are in the latter category, spend the few extra hundred bucks and replace the camshaft too.

Terry Ingoldsby
terry.ingoldsby@DCExperts.com

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #10
JuancarlosMGB Juan Carlos Perez Velasquez Madrid, Madrid, Spain Sign in to contact 1974 MG MGB GT "El Cherada" 1978 MG MGB Racecar "El 81 De Carrera" 1995 Honda Civic "Beasty Boy (Race Car)" 1999 BMW Z3 Coupe "BATMOBILE"	Topic Creator (OP) Mar 31, 2015 02:34 PM Joined 16 years ago 1,580 Posts

In reply to # 2953142 by dipstick Hi Juan,
- The pictured lifter is clearly failing, the hard surfacing is flaking away.
- #4 & #5 are exhaust lifters; I am wondering if those exhaust valves are making slight contact at full lift with the block surface and/or the pistons? I think I recall that the cylinder head was recently resurfaced which brings the exhaust valves closer to the block. With a dial indicator on the valve spring retainer, zero lash, bring the exhaust valve to full lift, with a pry bar (big screwdriver) on the retainer and push the valve down until it contacts either the block or piston and make note of the dial indicator movement. Ad the recommended lash to that number; there should be .080" clearance. Some folks use .060" clearance depending on valve weight and/or spring pressure.
- FWIW I have successfully installed new lifters on used camshafts, I don't want to get into a big discussion about this procedure.

You remeber right. I resurfaced the head 1mm. I checked the valve to block clearance; but I found that with my 0.04" obervore, the valves were self contained into the cylinders. But maybe with the heat, the valvez expand more than cylinder walls; or maybe the head moved enough to change things. Maybe I need to resurface the block eyebrows.
Nevertheless, I didn't find any evidence of valve interference in the cylinder head or block...

Edited 1 time(s). Last edit at 2015-03-31 02:36 PM by JuancarlosMGB.

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #11
JuancarlosMGB Juan Carlos Perez Velasquez Madrid, Madrid, Spain Sign in to contact 1974 MG MGB GT "El Cherada" 1978 MG MGB Racecar "El 81 De Carrera" 1995 Honda Civic "Beasty Boy (Race Car)" 1999 BMW Z3 Coupe "BATMOBILE"	Topic Creator (OP) Mar 31, 2015 03:12 PM Joined 16 years ago 1,580 Posts

Terry: You are totally right; but maybe in this case the damage is not so terrible. I measured the cam from heel to lobe and I got values between 33.30 mm and 33.32mm (exactly the tolerance of my caliper. So I hope I will be ok with the same cam. However I will have my eyes wide open with this engine.

In reply to # 2953174 by ingoldsb I think the answer to your question is, how much do you want full performance and life from your engine? Some people are more than happy with a car that runs reasonably well, and they drive the car so occasionally that lifespan isn't an issue. Others want the engine to run the best it can and last as long as possible. If you are in the latter category, spend the few extra hundred bucks and replace the camshaft too.

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #12
ingoldsb Terry Ingoldsby Calgary, AB, Canada Sign in to contact 1971 MG MGB	Mar 31, 2015 04:29 PM Top Contributor Joined 20 years ago 20,149 Posts

Juan, I think your reasoning is sound. What's the worst that can happen? - you have to change both tappets and camshaft later on if it doesn't work out. So, you would waste a set of tappets, but that isn't a disaster.

Terry Ingoldsby
terry.ingoldsby@DCExperts.com

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #13
Perdido Rut Rutledge Tuscaloosa, AL, USA Sign in to contact 1960 Austin-Healey Bugeye Sprite "Scarlet" 1962 Triumph TR4 1966 Triumph TR4A 1966 Triumph TR4A & more	Mar 31, 2015 04:35 PM Top Contributor Joined 16 years ago 5,263 Posts

Juan,
If it were my car I would replace the lifters with a quality APT set and plenty of lube, break the engine in for 20 min at 2000 rpm or so and drive the car. If the cam is bad or starting to wear you will find out with more frequent valve lash changes. This will buy you more time to decide what you want to do in the end if cam replacement is not an option.
Rut

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #14
Denis Denis Hill Bearii, Nth Victoria, Australia Sign in to contact 1968 MG MGB MkII 1973 MG MGB V8 Conversion	Mar 31, 2015 04:35 PM Top Contributor Joined 18 years ago 2,952 Posts

Juan Carlos, those old cam followers look to me to have insufficient curve in the face. The contact face should be slightly convex to match the cam lobe.
The good followers from APT are tough and the correct shape. If your going to reuse the cam and have it out I would at least polish the lobes to remove any tiny embedded wear particles. Denis

68 B roadster, Daffodil yellow, supercharger, Burgess SC head, SC cam, Mikuni HSR 48 carburetor and engine built for supercharging.

73 BGT V8 conversion starting with a bare shell. Built the engine "3.9L Rover" early in 2016 with high comp pistons and a few other nice bits, plus a T5 ford trans. Started on the body late 2016 and complete late 2017, Did all the work myself, mechanical, body. paint etc.
Finished and going well, great to drive and quick. Now has a nice 3.23 LSD.

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Re: Found Bad tappets; but cam looks and feels perfect. What should I do? #15
fast-MG.com Dave Headley Cortez, 4 corners, Colorado, USA Sign in to contact	Mar 31, 2015 04:50 PM Top Contributor Joined 15 years ago 9,605 Posts

Juan, how did you go about breaking in the cam and lifters? What idle RPM do you use? What are your valve spring load specs? Any sign of spring coil bind?

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