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1972 Midget Engine Issues

Maraldo

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Hi...this is a repost on recommendation from the MG General Thread. Picked up a ‘72 midget ~2500 miles ago...ran beautifully...about a month ago, the fuel pump went...no issues replacing. The following week it started to ‘choke’ as i was driving...would bog down and then catch and run even again...this was an instantaneous event...happened three times across a 3 mile stretch of road and then just died. Rebuilt the carbs...pulled the shafts (felt like it was taking on air). Finally brought it into the shop...he pulled the plugs/gaskets and looked down the Cylinders...said two had no finish with significant pitting...80% by pass. His recommendation was finding someone to do the honing or replace the engine. I have checked the fuel system and the wiring...inspected the springs and the pistons. Mechanic still comes up with the pitting is causing gapping creating no utilization of 2/4 cylinders...and that engine is struggling to run on the other 2. Have known the mechanic for many years...trust is not an issue.. Thanks all!!
 

Boink

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And the compression in all 4 cylinders is ____________??? Too easy not to check.
When you report that he pulled plugs "and gaskets", what do you mean by pulling gaskets? Was the head removed?
All that written, given your description of its sudden nature, I'd also be looking at fuel and spark too.
 

pdplot

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Look at the plugs to see what cylinder/s are not working.
Your fuel pump may be a loser. Check it out.
Your coil may be overheating.
You may have foreign matter in your gas tank closing off the fuel opening from time to time.
Remember the Old Mantra "If it's got gas and got spark and they both get there about the same time - it's got to run."
Bob Claffie is right. Start with the little obvious things before a teardown and rebuild - unless you were planning to do a major overhaul anyway. (We love these mysteries - it could happen to any of use, and probably will sooner or later.) Just be sure to follow through and tell us what it was when you find the problem.
 

SD Bugeye

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So this pump you replaced it with. what is the pressure output.
anything more than 4 psi could be an issue
 

Joe Schlosser

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Just mu two cents
Pitting causing loss of compression is not something that happens in 2 weeks. If it was running well and then all of a sudden stopped running well there should be another issue that you need to find.
Pulling everything apart tp fix the compression issue (you never mentioned the values) is fine but what is causing the problem will most likely still be there.
My rule is that it is the last thing you touched. In this case the fuel pump. Sucking air" not enough flow or too high a pressure? Why rebuild carbs before checking for other causes.
Carbs like cylinder walls do not just stop working.
 
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When you said 80% by pass, it suggests that maybe he did a leakdown test. However, leakage can occur between cylinders (with a blown head gasket) or past valves. I would perform a leak down test again and listen carefully to identify wear the air is going (crankcase, intake, exhaust, OR nearby cylinder)

Trusting a mechanic to be honest doesn't mean that he is infallible.
 

Bob Claffie

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Sounds to me like the original poster has his head made up and no matter what we suggest he is going to stick with his veteren machinist's idea. I wash my hands of this problem.
 

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Sounds to me like the original poster has his head made up and no matter what we suggest he is going to stick with his veteren machinist's idea. I wash my hands of this problem.

Agreed. Many things to check (or eliminate)... milky coolant, leak-down, compression, condition of plugs, etc. (all easy to check).

In my own case, I had the dreaded head-blanking-plug recession problem which created a similar sputter (as there was leaking across the two middle cylinders - instantly obviously upon remove of the head). The sudden nature of the problem should be telling.
 

LarryK

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Might even be something in the fuel tank. If it ran good to begin with, nothing wrong with engine.
 

Bob Claffie

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Appears we will never find out the real problem or solution.
 

LarryK

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:sorrow:
 
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