A15 motor in my Midget - more problems again! : MG Midget Forum : The MG Experience

A15 motor in my Midget - more problems again! #1
rbastedo Rick Bastedo Snoqualmie, WA, USA Sign in to contact 1980 MG MGB	Topic Creator (OP) Jul 29, 2014 02:48 PM Joined 16 years ago 1,949 Posts

It sounds like a helicopter or an old peugeot!
Saturday I returned home after 15 days in Alaska and then on Sunday I ran my car out about 80 miles to my mother in law's 81st birthday party.
It was running great - part way.
I returned on the ferry and when I started up the car it sounded rough, and had less power.
It idles fine, but revving it sounds like "puh puh puh" instead of the normal "vroom".
It burns oil and last time it had similar symptoms I replaced the plugs and it ran fine.

I've replaced plugs, put a spark tester on and verified I have spark at all 4 plugs, checked the carbs and they are fine.
Next I plan to check my compression at all 4 cylinders to make sure something in there hasn't broken.
Just strange it ran so great until I got on the ferry then like crap when I got off it.
The only other thing I did was fill up with gas over there but that was at a large chain so I don't really suspect the gas.

Any other thoughts?

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Re: A15 motor in my Midget - more problems again! #2
58custom Tom Crocker Santa Clarita, SoCal, USA Sign in to contact 1969 MG Midget	Jul 29, 2014 03:00 PM Joined 16 years ago 1,400 Posts

Spitballing...

Crap in the carb, maybe blocking a jet.

Crap in the fuel line before the pump. Filling up may have stirred up something that might have gotten caught in the line or pump.

Bad condenser or points closing. Or do you have electronic ignition?

Timing chain skipped a tooth. That this happened after the engine was turned off for the ferry ride is typical for a timing chain event, but the A15 has a tensioner so I guess it would have to be really worn in there.

Bent pushrod or loose rocker. (unlikely)

1969 MG Midget with Datsun A15/5 speed

Edited 1 time(s). Last edit at 2014-07-29 03:02 PM by 58custom.

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Re: A15 motor in my Midget - more problems again! #3
rbastedo Rick Bastedo Snoqualmie, WA, USA Sign in to contact 1980 MG MGB	Topic Creator (OP) Jul 29, 2014 03:48 PM Joined 16 years ago 1,949 Posts

Electronic (matchbox) ignition.
I can put my timing light on as well as check my compression.
If I have a valve or rocker or push rod problem my numbers will be way off for that cylinder.

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Re: A15 motor in my Midget - more problems again! #4
58custom Tom Crocker Santa Clarita, SoCal, USA Sign in to contact 1969 MG Midget	Jul 29, 2014 04:38 PM Joined 16 years ago 1,400 Posts

Timing light would reveal large discrepancy between spark and balancer, compression would reveal more about that or rocker/pushrod condition.

Also check the plug and coil wires for leakage to ground and maybe swap on a spare car & rotor.

After that you gotta get dirty. If fuel level in carb looks good (so then fuel pump & delivery is OK), consider blockages in carb passages. I don't recall if you have one carb or two.

1969 MG Midget with Datsun A15/5 speed

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Re: A15 motor in my Midget - more problems again! #5
rbastedo Rick Bastedo Snoqualmie, WA, USA Sign in to contact 1980 MG MGB	Topic Creator (OP) Jul 29, 2014 04:44 PM Joined 16 years ago 1,949 Posts

Twin HS4's and they are working good and "seem" to have plenty of fuel.
I'm thinking timing or valve related, I'll rule them out or in before looking at carbs.

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Re: A15 motor in my Midget - more problems again! #6
AN5L8016 Mark Haynes Nederland, CO, USA Sign in to contact 1958 Austin-Healey Bugeye Sprite "Bertie"	Jul 29, 2014 04:53 PM Top Contributor Joined 11 years ago 1,454 Posts

I'd guess at a loose valve adjuster, not having heard it.

'58 Bugeye
'05 Mini Cooper S

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Re: A15 motor in my Midget - more problems again! #7
rbastedo Rick Bastedo Snoqualmie, WA, USA Sign in to contact 1980 MG MGB	Topic Creator (OP) Jul 29, 2014 04:56 PM Joined 16 years ago 1,949 Posts

I've been really distrustful of the last rocker bolt, it seemed to not be 100%.
I'll start with a compression check on cylinder #4.

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Re: A15 motor in my Midget - more problems again! #8
randykieling Randy Kieling Grants Pass, OR, USA Sign in to contact 1957 Renault Next "Pierre" 1959 Morris Minor 1000 "Branson" 1960 MG MGA 1962 Austin-Healey Sprite & more	Jul 29, 2014 05:11 PM Joined 11 years ago 904 Posts

oil in the dash pots?

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Re: A15 motor in my Midget - more problems again! #9
BlueMax1 A G (Disabled) (Disabled) Disabled Account, Antarctica Sign in to contact	Jul 29, 2014 06:05 PM Joined 12 years ago 814 Posts

Old Peugeot, I wish!!

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Re: A15 motor in my Midget - more problems again! #10
66jalopy Phillip Jolliffe Lake City, FL, USA Sign in to contact 1956 Morris Minor	Jul 29, 2014 07:19 PM Joined 11 years ago 6,727 Posts

48 years later I'm still trying to forget that Peugeot 403, luckiest day I had with it it caught fire and I never had to drive it again! (It was my company car).

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Re: A15 motor in my Midget - more problems again! #11
Billm Bill Masquelier Santee, CA, USA Sign in to contact 1960 MG MGA 1600 1965 MG Midget MkII 1966 Austin-Healey Sprite "Sprite" 1966 Austin-Healey Sprite "Sprite"	Jul 29, 2014 07:35 PM Top Contributor Joined 17 years ago 4,473 Posts

Rick
How did it sound when you changed the plugs?
Bill

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Re: A15 motor in my Midget - more problems again! #12
rbastedo Rick Bastedo Snoqualmie, WA, USA Sign in to contact 1980 MG MGB	Topic Creator (OP) Jul 30, 2014 12:51 AM Joined 16 years ago 1,949 Posts

Bill, exactly the same

I did a compression test, have about 20 lbs in #4.

That last rocker bolt was always iffy, I guess it came loose.
Any thoughts on securing a stripped out rocker bolt in an aluminum head?

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Re: A15 motor in my Midget - more problems again! #13
66jalopy Phillip Jolliffe Lake City, FL, USA Sign in to contact 1956 Morris Minor	Jul 30, 2014 06:14 AM Joined 11 years ago 6,727 Posts

Two ways, if possible you can go with a slightly larger bolt, sometimes using a SAE instead of a metric and tap for it will do it. Helicoil back to original is the other. I would have a machine shop do it for me.

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Re: A15 motor in my Midget - more problems again! #14
rbastedo Rick Bastedo Snoqualmie, WA, USA Sign in to contact 1980 MG MGB	Topic Creator (OP) Jul 30, 2014 09:01 AM Joined 16 years ago 1,949 Posts

Maybe a slightly larger bolt would work, it has to fit through the rocker pedestal though.
If I'm getting a little thread would any form of locktite possibly do the trick?

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Re: A15 motor in my Midget - more problems again! #15
66jalopy Phillip Jolliffe Lake City, FL, USA Sign in to contact 1956 Morris Minor	Jul 30, 2014 09:24 AM Joined 11 years ago 6,727 Posts

I wouldn't think lock tight would do it. With pedestal off see if there are any good threads dealer in the head by screwing the bolt in, there may be enough to use a slightly longer bolt. You may have to cut a longer one down a little, then you could use locktight.

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