Oil pressure issue / motor rebuild

[MrDavo]

I've left the gallery plug out for now, so I'll get plenty of warning before the oil goes upwards, just seeing some in the gallery would be an improvement.

Triggers 20 percent rebuild rate due to no oil pressure on rebuild worries me. I'm going to drop the pump again at the weekend, I want to double check the feed side is primed ok, I may take the stopper valve out while it's submerged in oil, then replace. I'm going into town soon, a tub of Vaseline may be on the shopping list

[K2-K6]

I hate that feeling if the pressure does not come up as expected, leaving you trying to decide if to investigate further or still try to get the light out.

Vaseline is not a bad method,  I have always worked on V8 Rover engines on which it's a prescribed method of priming the oil pump after assembly. It's odd on that as the pump is a paired gear type which builds no suction when empty so absolutely requires this method. You even have to be careful during oil changes to make sure the oil filter is not taken off with the sump empty as the oil in the pump head will run back down the pickup tube to the sump and require dismantling the pump to get it going again was a Vaseline repack.

Oil pumps generally aren't total displacement devices and don't really start working well until dynamic sealing with oil when spinning gets them to deliver at the expected volume. One way of priming any type of pump is to fill via the outlet then spin it so the vacuum starts to pull the feed through. I appreciate that you can't get to that side of the pump in this case, the nearest I could get to that was as I wrote previously of trying to fill the oil filter first and reassemble to see if any of that oil would make that sort of arrangement.

Further thoughts are to point a fan heater at the oil tank for half an hour to get the oil less resistant to pumping. Put a piece of tube onto the tank breather with a tire valve in it to pressurise the tank by a couple of psi and force the oil to go through the pump as you turn the motor over.

The design criteria of an oil pump requires that you, within reason, turn it continuously to get the following system to prime from empty (it's that oil within the total system that prevents a run back of oil when you stop any motor) so you may need a team of kickstarters to work in relay to get the pressure up, or spin it on the starter motor.

The killer on these is that the oil restrictors to the head are blocked (covered in other posts on here) and prevent one or both sides of the cam being oiled. That won't show on the oil pressure light anyway as the gallery pressure still builds with them blocked. Don't think you've even got oil near there because your gallery is empty.

Just a further thought,  the motor running while shredding the original bearings.......all that scrap will have passed through first the scavenge side of the pump as it was recovered from the sump....... and then again through the pressure side of the pump on its way to the filter BEFORE it was caught in the filter material. Can you see any effects of that inside the pump?

Just remembered that pump was giving you a low / flickering oil light during running before you stripped it if I recall correctly, you need to be certain that's not going to catch you out now.

[MrDavo]

There was some marking of the oil pump end plates, but it wasn't bad, and the wear on the rotors was low, I don't think it got to run sick for very long at all.

I did some Googling of priming oil pumps with Vaseline, and got several  results from US V8 forums, apparently old Buicks and the like can only be primed this way, though there were still posts from good old boys who thought Vaseline was for sissies, and had never used a torque wrench because pappy said so.

Pump off, gloves on, pump apart and I packed the stuff into the inlet until it came out of the port in the pump, same from the engine side after undoing the spring to the stopper valve. Put it back together and packed it between the rotor and the outer, end covers back on, and slightly turning the pump caused Vaseline to rise from either port. In case I got an air lock in the oil line, I got the pump mostly on but not all the way, I put a bit of oil in the tank, once it started coming out all over the oil pump I pushed it up and tightened the bolts.

Sump plate back on, then I put a pint of oil in, some into the gallery (bike was on the side stand), some into the cam box to drain back down.  A few kicks and oil started coming back out of the gallery - result! Put the gallery plug on, lots more kicks. Checked the oil light, well and truly out.

I could hear gurgles from the cam box, and saw a weep of oil around the rocker spindles. There was a trace of Vaseline floating on the oil in the tank, which can only have come via the return, so that side works too.

At the start of this thread, the oil light was staying on up to about 1200 rpm, albeit with hot oil. I can now make it go out with 3 kicks, using cold 20/50. Eventually I tried the starter (coz my leg hurt), it struggles to get going, then spins happily, if slowly. I hate to think how it would cope with the plugs in. Trigger will be along soon to tell me off, I didn't do it for long though.

I'm considering changing the oil to 10/40 - I used 'Classic' 20/50 because it was what I had, bought when I had low pressure. Now I'm worrying I may have too much oil pressure, leading to leaks or hard starting  It would be kinder to use a thinner oil I'm sure, particularly while it is as tight as a tight thing. It span over much easier when I had no oil circulation, so I reckon its the cold thick oil being a bugger to pump round, not an over tight engine trying to seize! (that reminds me, a line on Westworld last week that made me laugh, when someone asked if the glass was half full or empty - 'We are engineers, the glass was designed to the wrong specification!')

If I do drop the 20/50 you can be sure  wont be letting the oil pump run dry. I haven't seen a ton of oil upstairs but I'm guessing I wont, at least until its been turned over a lot. The fact that there is any sign of oil coming from the spindles can only be good, though.

[Trigger]

So you did not believe me about the Vaseline and had to question my advise
20/50 is OK if you are running the engine in, in the summer months. You still need to see loads of oil at the cam

[MrDavo]

Hmm, that didn't go too well. 

I left the battery on trickle charge overnight, just went out to the garage, 12.5 volts, barely turns the engine over at all with the cold thick 20/50 in it, no spark plugs. That can't be right.

I'll try it with 10/40 when I get some, it span over quite happily when it didn't have oil pressure, but I am worried. One extreme to the other $@#~!

The O rings and carb top seals arrived this morning, trigger, thanks!

[Spitfire]

Mine's still running on Duckhams 20/50, used it since 1976 (not the same oil) though I will have to change over soon as my "stock" of Duckhams has run out.

Cheers

Dennis

[K2-K6]

That 12.5 appears too low for a battery that's just been charged.

A healthy one that is new will be about 12.95v with full charge and getting very much below 12.6v with no load would normally indicate that it really doesn't have much left in the way of starting grunt.

You could try jumping it off another vehicle,  the battery size (if bigger)  is immaterial but it will just turn over for longer before slowing down.

[Trigger]

I agree with K2-K6, your battery needs a big boost. You cant have too much pressure, that is what the pressure relief is for.
 

[MrDavo]

I put it back on charge last night. I just checked, 12.8 v, still struggling to turn the motor over at all. It's not a very old battery, but it is old tech, I managed to stain our stainless sink putting the acid in! I have seen a yellow glass mat one on eBay, I have a similar one on my Harley, expensive but bomb proof.

I can check the connections are tight try jumping from a car battery, but I still worry it's tight, and if it doesn't wiz round with a bigger battery I will try 10/40. Should there be an earth strap somewhere? We have a painted engine bolted in a painted frame when all's said and done.

[Trigger]

Yes, you need a earth from the battery to the frame. The eye of earth lead has the top rear engine bolt through it.
If you are confident that your clearance is spot on and oil is in full circulating , then hook a car battery up.

[K2-K6]

I've been using a Varta ytx14 bs which is a AGM battery on my cbx750.  It's one of the best batterys I've used on a bike with really good turn over speed and starting. The cbx doesn't have a kickstart and also a slipper clutch, so if I have to bumpstart it then have to push it about 30mph in second gear to get it to go! It just always spins and starts with this battery unlike mixed brand stuff I've had before. Some of them haven't even lasted a year.
I'm reluctant to call things rubbish,  but most of the batterys I've had before come very close to it but this one is great and about £44 delivered. Don't know how that compares to a moto bat cost wise.

[MrDavo]

I'll root around and see if I've missed an earth strap in the parts box, I'm sure we didn't fit one.

I can't see it in the parts book, give us a clue if you know where it is, but I know it's important on the 911, there's a copper braid strap beftween the gearbox and the chassis, and the starter doesn't behave if it's not there, because of the high resistance path between the starter and the battery negative terminal. As I see it, we have the same situation here, I'm guessing it wasn't as important with the exhaust on, it's steel, and bolted to the motor and to the frame at the same time, both metal to metal. Anyway it should be put right, as I say we currently have an earth path back from the starter through a painted motor bolted to a painted frame. Now I think of it, the triangular plate at the front offside mount was missing some paint where the engine bolted to the frame, so I gave it a good coat of satin black.

If I have to I'll order a 911 one, hopefully someone can suggest a cheaper alternative, as any Porsche part is reassuringly expensive (but the highest quality).

Edit just seen Triggers post, not sure where my earth lead goes at the moment. I'd file the paint off the engine mount (that bloody paint causing trouble again) but it's in now.

[K2-K6]

You can do a quick and dirty test by putting a jump lead from battery negative terminal straight to the sump plug to give you earth bypass and see if it improves.
Cars,  I always fit two separate earth leads to make sure it's got redundancy from running a rally car,  if one gets snagged or compromised it'll still start.

[MrDavo]

That's a good idea.

The Harley has two earth straps as well, but it is a fully rubber mounted engine, so it wouldn't work without.

[Trigger]

You can do a quick and dirty test by putting a jump lead from battery negative terminal straight to the sump plug to give you earth bypass and see if it improves.
Cars,  I always fit two separate earth leads to make sure it's got redundancy from running a rally car,  if one gets snagged or compromised it'll still start.

Why run a earth to the sump plug, when you can earth out the starter motor