[TR] Oil Pressure Loss

david brady dmb993 at earthlink.net
Sat Dec 24 08:15:29 MST 2016

Hi Folks,

Big blunder on my part. Long story short, I inadvertently started the 
cold engine with the oil pressure tube disconnected. Runtime maybe 15 
seconds with a couple of low rev throttle blips. I noticed a smell so I 
immediately checked the oil pressure gauge saw no pressure so I  shut 
off the engine. The smell was oil leaving the engine. I started the 
engine outside the car with the bonnet open which is typical for me. I 
need to manually hold the weber chokes shut with my hand as I turn over 
the engine.

Here are the particulars:

1) cold engine
2) seven quarts of fresh 10w-30 Brad Penn oil in sump
3) start engine, maybe 15s (probably less) of runtime, no-load
4) 3 quarts of oil pushed out the oil pressure gauge fitting
5) engine has cam bearings.

I replenished the lost 3 quarts of oil, started the engine, and went for 
a 20 mile drive. No external signs of anything wrong. Engine runs great.

Several questions:

1) with the oil pressure loss out the disconnected fitting is there any 
chance of even a dribble of oil being fed to the oil galleries?
2) I understand about oil flow rate being important and about the 
hydrodynamic oil film required with plain bearings which actually 
generates the oil pressure in the bearing's oil film itself. I'm more 
concerned about the heat buildup at the bearings due to lack of flow. 
What are the chances of bearing damage due to heat buildup in this case?
3) which bearings would be the first to show damage? Main, connecting 
rod, cam?
4) is it recommended to drop the sump and roll out a bearing to check 

Here's how it happened: a month or so ago I was testing the accuracy of 
my oil pressure gauge so I bolted on a new gauge. I then ran my tests 
and disconnected the tube from the crankcase in preparation to reconnect 
the stock tube, but I was then pulled away from project and failed to 
reconnect the stock pressure gauge tube. Fast forward a month and I 
completely forget that the engine's not buttoned up and I start the 
engine! Yikes!

Thanks for your input,
Merry Christmas,
'68 TR250

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