Oil Pressure for B18 engine in Amazon

[Rick Arizona 122s]

I appreciate you comments and realize that my initial description of what we had done or not done was quite vague, and perhaps somewhat misleading. I too had been wondering if there could have been too many cooks in the kitchen, during the engine overhaul. The mechanic I used is just a mobile tractor and backhoe mechanic, not a full time engine builder. While doing a repair on our old 1974 backhoe, he had said that he would be willing to help rebuild the old Volvo engine.

The automotive machine shop had been so busy that he said he would only have time to do the machining, not reassembling the engine. I probably should have been patient and waited 6 months or so until he had time to do it all.

Back in about 1970, I had once pulled the pan on my old 1960 MGA with the engine still in the car. I had wondered if it might also be possible to do that on my 1965 Volvo 122s. I had considered possibly checking the several parts you mentioned. I had not considered the possibility of dropping the whole crossmember, although perhaps if I decide to do that, I might also be able to replace the worn out rubber bushings on the front suspension at the same time.

The engine in my old MGA does remind me quite a bit of the Volvo B18 engine. They are both 4 cylinder engines with solid lifters and twin S/U carburettors. The Volvo was still running reliably until 1992. After that I left it sitting outside under a car cover for 25 years, until I managed to get it running again, by myself. Fortunately, cars do not rust much in Arizona and the body is still in perfect condition.

Soon after that, the mechanic and I disassembled the engine. We were surprised to find broken piston rings in all 4 cylinders, as well a piece broken off of the piston in cylinder #3. The timing gear on the end of the camshaft was loose and about to fall off. Later discovering the wrist pin bushings all being loose was also a surpise.

[Rick Arizona 122s]

I noticed just now that you had also posted a link to an excellent discussion about engine rebuilding on the MGB forum. I see that one of the posts suggested using a plastigauge on every bearing (unlike how we did it). Another post recommended double checking the machinists work with a plastigauge.

The posts about how to do pre-assembly checks of the oil paths through the engine to check for blockages were also interesting (which we did not do). Contemplating that possibility, I am inclined to think that if I had a blockage downstream from my oil pressure sending unit, I would not have a low oil pressure reading. But, if the blockage was upstream, a low pressure reading would make sense.

I do see the section in my Hynes manual about removing the sump with the engine still in the vehicle.

I have also wondered if perhaps there might just be various slightly off tolerances and modest amounts of wear here and there throughout the engine causing the slight oil pressure problem. In that case there might not be any easy fix, other than using 20W-50 oil.

[Vintagewrench]

Originally Posted by Rick Arizona 122s

I noticed just now that you had also posted a link to an excellent discussion about engine rebuilding on the MGB forum. I see that one of the posts suggested using a plastigauge on every bearing (unlike how we did it). Another post recommended double checking the machinists work with a plastigauge.

I have also wondered if perhaps there might just be various slightly off tolerances and modest amounts of wear here and there throughout the engine causing the slight oil pressure problem. In that case there might not be any easy fix, other than using 20W-50 oil.

Rick, I would guess that the crank journals and maybe cam journals and bearings are on the loose side of Volvo's recommended specs. Possibly that and maybe Murphy's Law is working against you.

Being in the trade I have seen this scenario unfold many times when I take in engine for a client and those entering the engine shops of friends. Most of the previous rebuilding work was done OK but due to the lack of time or measuring tools many engines end up like this.

I would circle back and check the rocker arm bushing to shaft clearances and to see if they are loose, many w/high mileage are. It is easy to do and doesn't take much time. If the shaft is worn get a new one and have a machinist put in new rocker arm bushings and hone the ID until the correct clearances are achieved. If this brings up the oil press up by only 5 psi you will be back in spec.

Volvo did state that a B18 can have oil press. as low as the single digits at idle when hot.

I had a '63 122s years ago that the entire service history was known and the engine was completely rebuilt at 125K miles, and later had a ring and valve job at 180K. I bought it at 210K and ran over another 150k and most of the time it had only had 1 to 3 psi oil pressure w/20/50 when hot (the oil light would flicker at idle) and I added a Stewart Warner gauge - it was also checked by hooking up another known good gauge w/the same result. At 65mph it only had 28psi !!! It ran really well until it needed another valve job and the rings began breaking (common) - thats when I parked it because the rest of the car was all used up to.

[Rick Arizona 122s]

Sometime in the next few weeks, when I get time, I will check the rocker arm bushing to shaft clearances to see if they are loose. I had this engine overhauled once before by a Volvo dealer, back in about 1974, so it probably has enough miles for those parts to be worn significantly. I would be quite satisfied with getting an additional 5 PSI (if that happens).

It was interesting to hear that your '63 122s which you bought used, ran for an additional 150K miles, despite oil pressure which was low most of that time, even when using 20W-50 oil. I had suspected that, even with less that perfect oil pressure, my engine will most likely run well for many years to come.

My '65 Volvo 122s is not my main transportation, so I do not expect to be driving it more than about 2 or 3 thousand miles per year, and do not expect to be driving it very hard. I plan to do some short to moderate length drives of about 100 Miles or less, each way, while mostly staying at about this elevation, or higher, in the mountains in Northern Arizona where it is cooler than down in the desert. I do not plan to wind it up to high RPMs for long stretches on long steep hills. I will be doing most of my day to day errands in my 1992 GMC truck or in the 2004 Volvo XC90. I hope the engine can handle that.

[blueosprey90]

A friend of a friend had a B16 engine laying around so I went to collect it.

There was also a sort of engine rebuild manual cobbled together from various sources. For all of the iterations of the B18 engine, the listed normal oil pressure at 2,000 rpm was 50 to 85 psi. The specified oil viscosity was listed as 10W-30.

Just posting because as far as I can see, my "service manual" for the B16 is silent on these issues.

[Rick Arizona 122s]

I went ahead and ordered the complete rebuilt rocker arm assembly and have installed it, but it did not make any significant difference in the oil pressure. It only took a couple of hours or so to replace the old rocker arm assembly with the new one, so trying that did not cost me much time.

I have not actually yet checked the rocker arm bushing to shaft clearances on the old rocker arm assembly. Checking the clearances first would have meant taking the assembly apart, and then leaving it disassembled for several weeks before the rebuilt assembly (or the parts) were ordered and arrived. Since those were 52 year old parts with about 250,000 miles on them I decided to just quickly replace it with the rebuilt rocker arm assembly, and see what happens.

From 1000 to 3000 RPM I get 10 PSI per 1000 RPM after I have been driving for over 30 minutes. So for instance, I get 30 PSI at 3,000 RPM. At 3500 RPM it briefly rises to about 35 PSI and then after about a mile or so, it seems as if the oil warms up more and the pressure drops back slightly to 33 PSI. At 4,000 RPM it also quickly drops back to about 33 PSI after the first mile or so.

At the moment, I have two oil pressure gauges installed, plus the oil pressure light hooked up. The electric oil pressure gauge reads about 1 PSI higher than the above readings provided by the mechanical oil pressure gauge. About two weeks ago, I added a sandwich adapter behind the oil filler, to provide more sensor ports. The sending units for the electric oil pressure gauge and the oil pressure light are each mounted in the sandwich plate adapter. The mechanical oil pressure sender is mounted in the threaded hole in the block where the original sending unit for the oil light was once mounted.

After returning from my test drive today, my heat gun showed a temperature of 212° F (100° C) when aimed at the oil filter. I have read that 212° F (100° C) is the typical oil temperature for most engines. The heat gun showed 182° F (83° C) when aimed the thermostat housing on top of the engine, so that would be my coolant temperature.

The oil on the dipstick looks normal, and is exactly at the full mark, so that would presumably eliminate a few possible rare problems such coolant getting into the oil, or overfilling the oil to where it was churned into somewhat of a foam.

So anyway, I will probably just use 15W-50 or 20W-50 oil during the spring, summer and fall. I have driven 800 miles since the overhaul, and at least the engine runs full power and sounds good.