American MGB Association Message Board

Technical Area => Engine Related Items => Topic started by: 2022 on May 07, 2022, 10:39:16 AM

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Title: Cranking Engine from under the Hood
Post by: 2022 on May 07, 2022, 10:39:16 AM
First of all, I must tell you, your videos are incredible, and have been a source of great information to me the past few years.

About 4 years ago, my dad called me to tell me he had found the "perfect" 1971 MGB in Rochester, NY.  The price was right, so I had him go buy it, sight unseen.  It was certainly more of a fixer upper than I anticipated (aren't they all!).
I did most lot of work myself, unless I had no clue how to do rebuilding the motor....which was seized, rusted, and generally in terrible shape.  I had someone tear it down completely down and rebuild it.

Now, on to my issues!  I've only been able to enjoy the car sporadically since getting it on the road two years ago.  It runs rough, lacks power, backfires, no one has been able to time it well, oil pressure now spikes up to max, and engine temp goes to max shortly thereafter.

This weekend I'll be changing the oil and the oil pressure relief valve, along with installing a new aluminum radiator and shroud.  I'm also going to do a compression test.  After reading up and watching videos, I fear that I have a bad head gasket between two of the cylinders.

My (first) question, if you have a moment, is simply to ask how you crank the engine from under the hood?  In your video, are you pulling the brown/white wire from the starter relay and grounding it?

Once I do the compression test, I'll set out to determine if my problems are engine, carburetor, or something I haven't even considered!

Thank you for your time!

Eric Lurie
Title: Re: Cranking Engine from under the Hood
Post by: JohnTwist on May 07, 2022, 11:16:48 AM
There are five factors that determine the condition of the engine:  Water leaks; compression; oil pressure; oil consumption; condition of the cam.

To spin the engine over from under the bonnet, they key does not have to be ON.  Remove the BROWN/WHITE wire from the starter relay (just to the rear of the fusebox) and touch it to one of the clips that holds the bottom fuse.  If the wire won’t reach, remove one of the PURPLE wires from the bottom of the fusebox and touch that WHITE/BROWN to that. 

Please call me so  I can help you diagnose what the problems may be – and to talk you through the OP valve replacement. 

John H Twist
University Motors Online
100 East Beltline Avenue SE
Grand Rapids MI 49506-2410
Cell  616 307 6737

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