Thread: Engine: 140 1986cc B20E: - Singing the no oil pressure blues
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Old Jul 27th, 2021, 04:15   #7
142 Guy
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Join Date: Jul 2020
Location: Saskatchewan, Canada

Time for an update.

First off, need to vent! The Volvo 140 service manual is slightly out to lunch in the section that covers replacing the sump gasket without removal of the engine. In step 4, the manual says:
Remove the rear bolts on the front axle member and screw on instead two auxiliary bolts (UNC 1/2-13x114). Remove the front bolts for the front axle member. Lower and remove the jack so that the front axle member is suspended in the two auxiliary bolts.

The 1/2-13x114 was confusing. I assumed that it was a typo that meant UNC 1/2-13x1 1/4. so I dutifully picked up a pair of 1 1/4 long bolts for the job. After doing this, I looked at the cross member with the car up in the air and thought "with the front bolts removed and a couple of 1 1/4 bolts holding the back of the cross member in place the cross member is going to drop in front and pivot up at the back. How is that going to make additional clearance to get the oil pan off". However, I figured perhaps that Volvo knows something I don't and a miracle occurs. Nope. No miracle occurred. With the short little bolts the cross member pivots up at the back reducing clearance as you lower the jack under the cross member. I put everything more or less back in place and looked at it and then went out and bought four UNC 1/2 13x 4 1/2" bolts. I replaced all the cross member bolts with the 4 1/2" bolts and then used the jack to lower the cross member straight down with the 4 bolts keeping everything lined up. That provided plenty of clearance to remove the pan. The other details that Volvo omitted were that I needed to remove 1 of the bolts on both the pitman arm mount and the steering box mount because the inside edge of both upper front A arm pivots was just catching on the bolt. I also needed to disconnect the sway bar to allow the brake lines to move as the cross member was dropping. If you are doing this, watch the brake lines very carefully. Depending on how far the front of the car is jacked up and the length of those four bolts suspending the cross member, the crossmember and by extension the calipers may drop enough that they rip the brake lines right out of the bulk head mounts. Mine were definitely tight.

In retrospect, I am wondering if 1/2-13x114 meant a 1/2 inch, 13 thread per inch bolt that was 114 mm long. 114 mm would be about 4 1/2 inches. Nothing like mixing imperial and metric measurements together for confusion.

The attachments show the fixture I fabricated from some scrap 2x4s and some hooks and chain to replace Volvo SVO 2727 which holds the engine up once you have disconnected the front engine mounts and lowered the cross member. Volvo just uses a rather small bolt at the top of the timing to suspend the engine. On the later B20 heads there is a mungo bolt hole at the top of the head on the right so I used that as the primary support with the timing cover bolt used to keep the engine level.

The rest of the operation went pretty much without a hitch, ignoring the 3 week delay in getting the pan gasket from Rock Auto after Fed Ex lost the first one. As to the cause of the low and then no oil pressure (during subsequent testing), that is a mystery. When I went to remove the oil pump and the feed line to the block, both rubber seals on the feed pipe were firmly in place. In fact, the B20 feed pipe has a ring on it on each end which backs the seals when the pipe is inserted in the pump and the block. You can't even see the seals when the pipe is inserted so I am thinking that there is pretty much zero possibility that the seals would ever pop out under pressure. When I unbolted the pump I had to give a very firm yank to get the feed pipe out of the block (same at the pump end). It definitely wasn't coming out on its own.

I installed the new pump and buttoned everything up with some new 5W50 oil. I modified a 12" flat blade screwdriver to allow it to be inserted down into the distributor drive hole and allow me to turn the pump by hand. I did a couple of CCW turns by hand and then the resistance increased as oil began to flow. I gave a few more turns and I could see oil flowing into the hole for the distributor drive gear (supply to the drive bearing) and oil flowing in the nylon line to the test oil gauge. I installed the distributor drive gear and my cam sensor carefully following the alignment marks I had painted on the distributor hole so I would not have to go through a timing reset exercise. With the cam sensor in I reconnected the battery and did a test crank of the engine. A few seconds cranking gave about 30 -35 psi on both the dash and test gauge. The battery was a little low after sitting for 4+ weeks so cranking was a bit slow. I disconnected the test gauge and reinstalled the oil pressure switch, reinstalled all the fuses that I removed for the initial pressure check and then fired up the engine. Start up was quick and the oil pressure rose to around 55 psi very quickly. I let the engine run to check for leaks and allow the coolant temperature to come up to around 90 C for a few minutes. With the engine idling at around 850 RPM oil pressure was rock steady at 55 psi even after the temperature had been up above 90 C for about 10 minutes. That is a definite improvement over the old pump as pressure would sag to around 30 - 35 psi at idle when hot.

I pulled apart the old pump to see if I could spot the problems for my low / no oil pressure. I was expecting to find a broken oil pressure relief spring; but, the check valve was intact. I looked to see if there were any objects holding the ball valve open; but, didn't spot anything. According to the service manual the tolerance on the tooth flank clearance is 0.006 - 0.014" and mine measured out at 0.013" on some of the teeth pairs; but, not all. Some of teeth pairs were tighter. The end float on the driven gear was between 0.002" (loose) and 0.003" (tight). The service limit is 0.004" so mine was within limits. The pump measurements were all within; but, close to the upper limit of the service tolerances. The pump wear probably lines up with the lowish oil pressures that I was getting at hot idle; but, I didn't see anything that would be responsible for the sudden drop in oil pressure that I experienced or the fact that during the test after getting the car home I was not able to generate any pressure of flow at all.

Out of curiosity I reassembled the old pump and then inserted the pump into a small pan that I filled with old oil. I rotated the pump drive gear and after a few rotations was able to generate flow through the pump. That is not a test of pressure; but, it is an indication that the pump could generate flow. Why I got the no flow results in my test remains a mystery. However, the new pump definitely does work better at idle than the old pump.
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Last edited by 142 Guy; Jul 27th, 2021 at 04:19.
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