QuestionQUESTION: Just had the above happen to me. At start up it ran at fast idle (approximately 3500 rpm) for about 6 seconds. Found out the oil pump not working. Could I have damage in the engine? What should I do to check? Remove main and rod caps? What about cam bearings. We used a lot of assembly lube when putting it back together.
Nervous Gary
ANSWER: Hi Gary,
Even though you have not told me what kind of car this is. It does not matter as all engines operate the same and the clearances inside are close to the same.
You are in the "MG" section and I have never seen a oil pump not work on any MG so you need to explain.
What did you do to the engine to have it down? and what kind of "assembly lube" did you use and on what parts? What kind of MG was this?
It is very dangerous to use any heavy grade lube on rods, mains or cam bearings. Assembly lube is ok in an oil pump and on cam lobes but dangerous to use on bearings as it ca restrict flow of oil in the first stages of preparing to run.
Any time you have had any engine apart you should disable the ignition and spin the starter until you see oil pressure on a hydraulic gauge. BEFORE YOU START THE ENGINE.
6 seconds is not usually enough to do harm but a running engine with no oil pressure will do major bearing damage in seconds. Especially if you used a heavy assembly lube on the bearings and shaft.
Howard
Howard
---------- FOLLOW-UP ----------
QUESTION: Howard,
Thak you for writing; it is a great help. Here is more information as I wrote to you the day it happened.
This is a 1964 MG B that is a vintage racer. We have gone through it entirely because of a spun bearing, and not knowing what the previous owner had done. Assembly lube was not thick. Taking the pump out showed that the mechanic had not primed the pump. He thinks I have lost confidence in him (have not-mistakes happen)and has given me back the carr with the comment that he would would also return the money I have paid him to date. He then left on a three week vacation and I have a race at the end of this month. He said he used plstigauge on the rods and they werre ok.
I have the ability and experience (on other engines) to work on it as necessary, but I am thinking it should be done by a very experienced person who can discern the smallest points of damage.
What do you think?
Gary
AnswerYes, I have seen a mechanic in one of the shops I worked in build an engine and he lubed all the bearings and forgot and put a clean dry pump in and could not build oil pressure even spinning the engine before fire up with the plugs out. All the mechanics in the shop got involved and he opened it up and what we found that lubing all the bearings made a air tight seal and the pump that was clean and dry tried to pressurize the oil galleys with air which it can't do and the air just gets back past the pump rotors and prevents any vacuum on suction side so it never drew any oil from the pan. It was good that he made it a policy to spin up to get oil pressure before fire up so no damage was done.
This is why many mechanics use a heavier lube to lube a pump then they do bearings. Some mechanics in the shops I have worked in only use the engine oil to lube the bearing and either white lube or even Vaseline to lube the pump when they are going to install the engine right away. But sometimes in a shop you will build an engine and it will sit for several days to even weeks before installing in a car so it is dangerous to use just oil in the bearings. Some mechanics even loosen an oil galley plug to allow easier oil priming. You can purchase a pressurized oil primer to pre-prime the oil galleys and system and some race cars have them on the engine to pre-charge the system when starting.
I conducted crude tests on clean metal back in the early 60s by coating clean metal with different lubes and just setting them outside for a month. The oiled pieces rusted in less then a week and the winner was STP oil treatment. So from then on I mixed a 50/50 oil/STP mix to lube cylinder walls and bearings especially if I knew the engine would sit for a while before installation. We always spin up for oil pressure before fire up though. Most British cars will get 35 PSI and higher just with the starter motor. We did Jag, Lotus and Alfa the same way.
I'm not trying to sell STP and I know it was designed to be a viscosity index booster to keep the viscosity up when the oil got hot and it does do that but I liked it for the fact that it stayed on metal for long periods of time. Even though the viscosity looks thick it can penetrate a space that 10w oil can't get into.
Howard
