QuestionQUESTION: I changed the oil pump not to long ago because the light was flickering on and off and the switch was fairly new. It ran fine for a few days, but now the light is coming back on again. I just replaced the switch but that doesn't make a difference. The engine runs fine except for a light valve tick that has been there for a while. Is it possible to the pump I bought is defective? I purchased it from Victoria British if that helps.
Also, I'm running 10w-40 even though the manual says to use 20w-50. Should I go even thinner for a better flow?
ANSWER: Hi Michael,
It is very rare to have a British oil pump bad. You need to at this time get a hydraulic oil pressure gauge and put it in place of the Oil light sending unit and check the oil pressure when the oil is warm.
You should see 25 to 35 PSI at idle and from 45 to 65 PSI at 2000 RPM. Anything less then that indicates a problem either with the bearings, the pressure regulator valve or something wrong in the rocker arms or shaft.
The pump can pump 350 to 400 PSI which would explode the oil filter so the factory installed a pressure regulator valve to control the pressure. When oil can not get through a good bearing because it has close clearances the pressure builds and the regulator valve opens and relieves the pressure. If however the bearings are loose the oil flows freely and no pressure is built up thus a warning light comes on.
If your manual says 20w-50 you should be using that not a thinner oil. The 20w-50 oil may put your light out but you still need to check the oil pressure.
Howard
---------- FOLLOW-UP ----------
QUESTION: I forgot to mention that a while ago, while I was replacing the timing chain, I had a paper towel in between the oil pan and the engine block to keep debris from falling into the front lip of the oil pan (it's a TR7 btw and as I'm sure you know, the oil pan bolts into the timing cover.) That paper towel fell into the oil pan. I didn't think anything of it at the time. IS sit possible that it's clogging the oil pick-up? I'm going to replace the oil pan gasket anyways, so I'll be sure to clean up as much as I can and check for any end play.
Thanks for the advice.
AnswerYes, definitely it could get pulled up to the pick-up and stop any oil flow.
If it were mine I would get some Plasti-gauge (available at most auto part stores) It is usually color coded and you want the "Green" (.001" to .003")
There is no instructions so this is what you need to do.
Remove one rod bearing cap, noting which way it came off as it must not be turned around. Tare off about one inch of the plastic green string and lay it across the bearing shell in the cap so it is not lined up with the oil hole in the crank. Put the rod cap back on and torque to specs. (45 ft lbs) BUT YOU MUST BE CAREFUL NOT TO MOVE THE CRANK EVEN THE SMALLEST AMOUNT! As that will destroy the test and you will need to clean off the Plasti-gauge and start over.
The plastic string will be crushed and then you tare off a small section of the paper cover with the gauge marks on it and compare how flat and wide the string was crushed. Use the inch gauge section on the paper. Ideally you would like to see 1 1/2 thousands (.0015") but up to (.0025) can still be used. Any reading higher then that is not going to stay together long. While you are there look for any scaring due to the lack of oil on the first test start up.
Lube the bearing but not much if you are using a heavy lube of some kind. I have seen the results of a mechanic who used "White Lube" to lube bearings when assembling and he over did it and forced a lot of it into the oil holes in the crank and he did not spin the engine to get oil pressure before starting up. The engine locked up and every mechanic in the dealership helped him pull it down and we found that the thick lube had stopped oil flow and was too thick to be forced out into the width of the bearing and both sides of the bearing gaulded and locked up on the crank.
Many shops and even production engine re-builders use white lube to assemble engines but they are careful not to get it packed into the oil holes in the crank.
WARNING! If the paper towel is shredded, you must remove the oil filter and look for any signs of pieces of the paper also in under the plate at the rear of the block that holds the oil light sending unit just back from the oil filter.
If you find paper shreds, you need to remove the oil pump and try to clean out all the oil passages in that area and in the pump itself.
Howard
