I replaced the oil pump on a Volvo 240. The oil pump is down in the oil pan underneath the engine. I followed the Haynes manual which said to prime the pump with Vaseline.

I put everything back together and turned the oil pump manually with a drill using the auxiliary drive which powers the oil pump and the distributor (while the timing belt was off). It was hard to turn at first as the Vaseline was used up.

I'm afraid the Vaseline has now clogged the line that goes from the oil pump to the oil filter in the engine. I verified that no oil was flowing by removing the oil filter and nothing came out when I turned the auxiliary drive.

I tried turning the oil pump with twice the amount of oil recommended in the engine just to see if that would be enough to build up pressure.

I also tried warming the oil to see if that would help melt the Vaseline.

What can I do to get the oil pump to work? I would remove the oil pan again only if I can't get anything else to work.

  • Are you sure you were spinning the oil pump in the correct direction? – Pᴀᴜʟsᴛᴇʀ2 Jun 3 '17 at 21:24
  • I'm sure, it's clockwise, same direction the timing belt goes. – willpb Jun 4 '17 at 0:59
  • Sorry ... had to ask :o) – Pᴀᴜʟsᴛᴇʀ2 Jun 4 '17 at 1:04
  • I am curious as to why the oil pump was replaced. – Inlandsmog Jun 6 '17 at 18:04
  • I took the oil pan off to try and stop an oil leak from the front main seal. I replaced the gasket for the front end cover that holds the front main seal and the seal for the auxiliary gear. The pump didn't have to be replaced though it was a little worn. – willpb Jun 7 '17 at 2:14

I do not think that Vaseline is thick enough and solid enough to withstand the normal pressure involved in the oil pressure system. I think you have a problem with either the new oil pump, or the installation.

Many years ago, when I was a young lad, we used to run diesel fuel in the oil pan to clean it out. During a normal oil change, if there was sludge and excessively dirty oil, we would remove the oil and replace it with diesel fuel to clean everything out. We were careful to only run the engine for a couple of minutes. We would then drain out the diesel fuel and replace it with motor oil.

I only bring this up as a possible way of checking out your hypothesis that the Vaseline is clogging the lines. The diesel fuel would certainly dissolve the Vaseline if that was the case.

  • Using Vaseline to prime an oil pump is very common. All it has to do is help create the seal. When the engine is warm enough, it melts right away for easy cleanup (inside the engine). Doesn't clog anything (like screens or filters). Works really well, especially if you are going to put the bottom end together and let it sit for a while. – Pᴀᴜʟsᴛᴇʀ2 Jun 3 '17 at 21:23
  • For assembling a bottom end, I used a product called "graphogen" - high quality graphite based grease that lubricates the bearings very well during initial start or spinning to bring up the oil. – Solar Mike Jun 4 '17 at 9:12

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