1977 MGB OIL PRESSURE

  • Tiny
  • cantjo
  • 1977 MG MGB

Engine Mechanical problem
1977 MGB 4 cyl Two Wheel Drive Manual 55348 miles

My 77B has high oil pressure. High being about 60psi at 1000rpm and 85 to 90psi at 3000rpm. I have checked the screen in the sump an it was fine. I replaced the relief valve and spring. I tried an engine flush. The thing that really bothers me is when I take the oil filler cap off I do not get any blow by or see any oil flowing. The older cars that I have owned when you take off the oil filler cap oil will blow out it. I have started and ran it several times for 10 to 20 minutes and it has not blown up yet. Does anyone have any suggestions?

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Tuesday, June 2nd, 2009 AT 4:25 PM

5 Replies

  • Tiny
  • Docfixit
  • Expert
  • 18,993 posts

According to the boys that built car
idle pressure 10-25 psi
Running 50-80 psi Did you replace relief valve spring? Was free length 3 in? Normal opening of relief is 70psi.
Have you checked with mechanical gague. Lucas the Prince of Darkness can't be relied on.

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Wednesday, June 3rd, 2009 AT 3:01 PM
  • Tiny
  • cantjo
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Yes I replaced the spring and valve that I purchased from MOSS. I also checked with a mechanical unit also and no difference.

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Wednesday, June 3rd, 2009 AT 3:45 PM
  • Tiny
  • Docfixit
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If no rocker arm clatter I go with it was engine recently rebuilt. You have solid lifters and oil comes up into rocker shaft not alot of flying oil. What viscosity oil and filter needs relief spring.

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Wednesday, June 3rd, 2009 AT 4:13 PM
  • Tiny
  • cantjo
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No it has not been rebuilt. The odometer only shows 55149 and I'm guessing that's correct. I have 20w50 in it and a Purlator L14670. It does have a little lifter noise until the oil warms a little but then it is quiet.

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Wednesday, June 3rd, 2009 AT 9:14 PM
  • Tiny
  • Docfixit
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  • 18,993 posts

Pull the rocker cover and remove rocker assembly. Clean it out slug can build up inside. And give it a valve adjustment. Couldn't hurt
Also recomend a Robert Bentley service manual pretty sure MOSS has

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Thursday, June 4th, 2009 AT 1:43 PM

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