Norm wrote:
> On Tuesday I took the Turner engine (in my MGB "truck") to a machine shop
> about 25 miles up Rt. 8 in Oakville, CT. I noticed that the MGB's oil
> pressure at 3500 rpm's wasn't very good once the engine got hot. Only about
> 50 lbs. Off the highway it dropped to 25 at idle. A lot lower than usual. I
> thought it might be from overheating oil, so took a minute, stripped the duct
> tape off the oil cooler & pushed it fully down to expose all rows. (In winter
> I retract it into the pocket I made in the bottom of the panel where in stock
> MG's it normally sits on top. It hangs below to keep the radiator clear & the
> 2 openings in the front valance feed air directly to the cooler. I install a
> duct from those openings to the cooler when racing.) That made a difference
> coming back - on the highway. Once on local roads the pressure again dropped.
>
> Wednesday AM, when I pulled off the highway it was at 15 lbs. WHAT THE HECK?
> Now this is an engine with something like 10,000 miles on it. Oil pressure
> should NOT be dropping like that. That night, I changed oil & filter (Only
> 3,000 miles since previous). I use Mobil 1, so 3,000 miles is no big deal.
>
> After the oil change, when I started the engine to check for leaks - pressure
> went to 100 LBS! WHAT? Then it fluctuated between that & 20 lbs. Absolutely
> crazy!
>
> Drove to work today & pressure was low normal. At traffic light off the
> highway - 10 LBS!!!!!!!! OH S - - - ! Consulted with my two best MG Brains
> during the day & we considered the following: A - something clogging the feed
> line to the pressure gauge (if so, 100 lbs. would be unlikely); B - a bad
> pressure gauge (a very rare occurrence) or C - a jammed relief valve (most
> likely).
>
> Just finished the repair. It was the valve. It had jammed so tightly that I
> had to use a thread tap to twist it out. The valve (piston-type) was badly
> scarred on one side. I guess I'll be changing the oil & filter again real
> soon. Used increasing grades of wet/dry sandpaper to deburr & polish it. Now
> re-installed all seems well.
I recommend the ball-bearing rather than the piston; it's not likely to
repeat the problem.
-Rock http://www.rocky-frisco.com
--
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