Cold Start Oil Pressure on Daytona or Centauro?

[Old Jock]

The reason for the question mark is I'm trying to find out what it typically is. So I'm looking for somebody with an early 4V engine that has a gauge installed

The mystery of low oil pressure continues on my Daytona RS engine. I'll spare the full details but after purchasing the bike I immediately installed Joe Caruso steel gears and DAS pump, at the same time installing an oil pressure gauge and a temp dip stick. The only thing I did before that was to start the bike and everything appeared fine, but I had no gauge on it at that point.

First start of the bike after the work, it showed pressure at 55psi, a bit low I thought but should be Ok, after about 20 miles and some traffic, I got the low pressure warning light and checking the gauge showed oil pressure below 10psi, an mmediate stop ensued. Oil temp when I got off to look was 120C (can't read it on the move). Waited for the oil to cool and rode home, by the time I was home oil pressure was about 25psi.

The DAS pump was removed and the old pump put on and the pump turned over with a drill on the nose of the pump (antclockwise facing the pump) at about 1500 rpm, about the same pressure was obtained (55psi)

Since then the pipework out my 1100 (relief valve, oil cooler and filter) were swapped over to the 1000, still the same result.

Next Roper (splash/sloppage plate) removed and I noticed one of the gaskets had warped where the gasket mates to the rear oil holes (return?) on the crankcase. New gasket installed Roper plate out and tried again, still 55psi.

Rear and front mains have not spun (I wondered if the anti rotation pins, especially the rear were installed). Everything as far as I could see looked fine when I peered into the engine from the bottom.

The only thing of note this time is when I spun the pump with the drill again was, oil was now flowing out the bottom of the front main. It was not a huge amount more of a dribble however I don't recall it doing that before on previous spins of the pump.

Engine has around 4k miles, so I would hope it's never been apart.

Starting to wonder now if stationary engine and spinning the pump would give me a significantly different pressure reading than a turning engine, because short of pulling the whole thing apart I cannot think of anything else that would result in low pressure

John

[John A]

I'd make damn sure the pressure reading stuff,  guage and all was dead reliable,  I'm beginning to suspect the mains unless there is an internal leak but I can't come up with a scenario of that.

[Old Jock]

The gauge and pipework is good John

The readings have been crosschecked using a different gauge, the result a little different about 3-5 psi but that's within the range of a commercial gauge and given I'm looking for at least another 15 perhaps 20psi it proves the pressure is low. The takeoff is at the normal point the pressure switch sits and 1/8" steel braided hose feeds pressure to an aftermarket switch and gauge. The hose was all new and installed by me so I know it's good. Used a similar set up on another 2 bikes now and it's been flawless

I'm absolutely stumped myself that's why I'm asking, but I am beginning to think that the engine will have to come out, both mains checked and probably big ends if I'm in that far too.

Any clues if the front mains can be pulled in situ, just for a look? I am in that far anyway

[Frenchfrog]

You can certainly pull out the front mains on a 2 valve John...sorry to hear that you are still up against this one !

[Frenchfrog]

I know you already posted about this ....there is no chance that the pressure release valve is the problem ?

[Chuck in Indiana]

I know you already posted about this ....there is no chance that the pressure release valve is the problem ?

It certainly *could* be. When I checked the Lario PRV, it was leaking badly. Lapping the piston back in cured it.

[jacksonracingcomau]

I know you already posted about this ....there is no chance that the pressure release valve is the problem ?

easy to check blow off but two are same
what does gauge read on 1100 with same. valve ?
bot and cold same oil

[Old Jock]

Oil pressure on the 1100 reads about 80psi on a cold start on the 1100 at idle around 1500 rpm.

In fact when doing an oil change and spinning the engine with the plugs out to obtain pressure on the 1100, the gauge will climb to 50-60 easily on the starter motor.

Given that I've tried 2 different relief valves, one of them a known good one, I would be very surprised if the relief valve was the problem

Spinning the pump to max speed (probably a little less the 3k rpms) the pressure will rise to 60. My take is the valve is still shut, a leaking relief valve could be an issue but I've tried 2 now, so I very much doubt that is where the problem lies

FrenchFrog, I've been pulled away from the bikes by other stuff, so it's more my inaction than continued fruitless trouble shooting. Thank you for the kind words

The relief is set at 5 bar on the 1000 and 1100 engines so pressure is really a bit over 75 psi static pressure. The reading of 80 on the 1100 sounds reasonable within gauge error or possibly a little different dependent on where the static pressure is measured

Oh oil is a 15/50 synth, same oil grade and brand in both bikes. I know recommendation is 20/50 but I run all my bikes on the same oil and up until now never had any problems

I think that I'm just going to have to man up and pull the bloody engine, but it's doing my head in. Before I do that I need to sort the woes with the 1100, which are truly odd as well but entirely unrelated to this issue.

Nice to be back anyway and hear from you all

John

[acogoff]

     I know it is apples to oranges, but on the Lycomings if some debris has run through the oil pump and scared it up inside, essentially giving the gear pocket way too much side clearance, the pressure will be great on startup but fall way way off into danger territory when warmer. Insert one of Chuck"s "shrugs" here.

[Rough Edge racing]

Starting to wonder now if stationary engine and spinning the pump would give me a significantly different pressure reading than a turning engine, because short of pulling the whole thing apart I cannot think of anything else that would result in low pressure

John

 It's normal practice with autos to spin the oil pump,if  possible, before starting a rebuilt engine to pre lube the internal parts...I have personally done this a number of times and noticed the pressure on a stationary engine to be about the same as a running engine on cold start...This may or may not apply to a Guzzi..

[Old Jock]

acogoff

I hear that but I have the same pressure reading using 2 different pumps, one of them brand new, my philosophy with the pump is the same as the relief valve, if I've tried 2 and they are both telling me the same thing then the possibilities of that component being the problem are pretty much reduced to zero

Oh and please don't think that when I counter suggestions I'm pouring cold water on them, far from it I'm open to all ideas and short of insults (& maybe not even then) any reply is welcome

Rough Edge Racing

That's really useful information and helps confirm what I'm seeing, even if you cannot confirm it for a Guzzi, it's still very much appreciated

In other words when I ran the engine I got 55psi idle cold start.

When I only spin the pump with the drill and the engine is stationary (the drill is spinning the pump to approximately the same speed as an idling engine) and I get the same result within reasonable bounds of error

John

[twhitaker]

I'm kind of surprised Howard R has not chimed in yet. He had an oil pressure problem with his Sport (Spot). IIRC, he surmised that his mains were turned to the low limits while the bearings were at the high limits and this lowered his pressure.

[Howard R]

I'm kind of surprised Howard R has not chimed in yet. He had an oil pressure problem with his Sport (Spot). IIRC, he surmised that his mains were turned to the low limits while the bearings were at the high limits and this lowered his pressure.

My situation was far enough removed from the OP that I didn't think I could offer anything constructive.  The front main journal was in fact machined about 12 thousands undersize, letting all the oil pressure leak out when hot.  In my case, said machining was accomplished by a tiny pinch of glass bead media somehow hiding from extensive masking/plugging of interior surfaces and holes, plus post-blast cleaning when I had the oil pan bead blasted.  Apparently the first stop was the front main bearing, and the babbitt did exactly what it was supposed to do, catching the beads.  Just so you don't have to try this at home, I can tell you that it will turn your engine into a 6,000 RPM crankshaft grinding machine.  (Yes, my problem was totally self inflicted.)

I'm sure the OP is nowhere near as stupid as I was.  I have, as noted a Sport 1100, and also a Centauro.  I run oil pressure gauges on both, and see about the same behavior from both.  Cold start 70-80 psi at idle and 45-50 psi at "Guzzi speed" (around 4,000 RPM) hot.  Same from the Centauro both before and after I got rid of the explode-o-matic oil pump gear and converted to timing chain & pump when I replaced the cam belts.  The Sport has about 100,000 miles more than the Centauro, so I have a ways to go before I can get exactly comparable readings on both.

Howard

[Old Jock]

I'm sure the OP is nowhere near as stupid as I was.

I would not place a bet on that Howard!!!

Your information is useful as you have given me what I thought would be the case, cold start 70-80 psi, where the relief valve is protecting the system from exploding

I think the way to probably go is try and pull the front mains, I'm pretty much there anyway and have a look

Then it's the dreaded engine out after I sort the 1100.

This has been very useful, if disheartening at the same time.

I know I've probably just been kidding myself and clutching at straws.

I need to check mains, big ends and crank sludge plug

Thank you all and again any other comments welcome

John

[jacksonracingcomau]

oil filter o ring not sealing ?
I would be pressure testing sump galleries before strip

[Old Jock]

I hear you and thanks for the suggestion Jackson Racing

Again as I changed over the whole internal pipework assembly from a known good bike (the 1100) to the faulty one and the oil filter is part of that assembly, that's another component that's been replaced and still I get the same result, so effectively ruling out any filter woes or leaks too.

I'm formulating a plan where I can pull the front main in situ and then the rear by crabbing, the big ends I could probably get to from underneath so no need to pull the whole bloody lump, but still a lotta work.

If I knew how to pressure test the galleries I would. I don't even know which holes on the feeds and returns in the crankcase do individually. Unless I could get a diagram showing where the individual galleries feed to and from I have no idea how I could complete a pressure test. I've never seen an actual flow diagram for the engine, schematics yes, diagram or cutaway no

John

[antmanbee]

If you have a pan off of a ev/jackal type engine you could test with out a lot of the later oilcooler type plumbing.
These are the pictures of the oil system I was able to locate.

[Old Jock]

Thank you very much antmanbee

These are useful and informative

I don't have an older sump that I recall, although I may have, if I searched through all the "munt" as Mr Roper refers to it

Pretty much beyond that state now anyway, during the last run with the pipework swapped over, the Roper Plate removed and a new gasket in the base where the pipework mates to the crankcase feeds and return, I was still getting the same result. The upshot of that is all the work I did was 100% sound, which was where I was certain the fault lay. This bike has obviously had this problem when I purchased it.

Next move is start pulling mains (front first) to see if I see any horrors lurking and just take it from there. Even if the front main is the problem I wouldn't be happy until I checked the rear and big ends too, as God knows what the problem was in the first place and what other damage has been done to the bottom end.

This is the second bike I've purchased that ran fine but had huge underlying problems. Both low mileage, it makes me wonder how people can make such a c**k up of the engines. The technology is "State of the Arc" and pretty much bombproof, yet still some people manage to do untold damage to them in short order, it beats me how they manage it

John

[John A]

So I'm setting here thinking about the low pressure.  Do you know any history of the engine?  You could make a list of what should and what should not cause a change as you change the components.  The frustrating part is that nothing you've done seems to affect it.  You mentioned the sludge trap,  maybe the trap is cocked up and leaking.  Could be a flow blockage or leak on the intake side of the pump causing a low pressure situation?

[Old Jock]

Hi John

No I don't know the history of the engine, it was imported to the UK from Japan. The mileage is a shade over 4,500 miles and the bike was sold by Magni to the main Japanese dealer on 25th May 2000. I beleive it then sat with the dealer for a few years then was registered and some mileage put on it. The rest is a complete mystery.

Yes most certainly a partially blocked oil way on the discharge side, a torn gasket, a faulty rubber seal where the filter mates to the housing, a blocked oil filter, a leaking relief valve or the pump not being on flush with the crankcase face or the bolts being loose. All would cause a low oil pressure, either through throttling in the pipework or spillage and loss of pressure (and incrceased flow) through insufficient back pressure being placed on the pump discharge. The thing is I've pretty much all but eliminated everything except a blocked oil way as it's next to impossible to do. However with the front mains out I can possibly see some of the passageways

Other contenders I've thought about are the sludge trap in the crank being loose, the anti rotation pins in the mains (they place a restriction on the discharge as I recall) or badly worn/wiped/scored mains and possibly big ends allowing the oil to leak out the bearings.

This is before we get to any plugs in the crankcase in the oil passage ways, but as far as I'm aware the oil ways are all cast into the crankcase, so short of a cracked casing (and I've never heard of that ever) the casings will be the last thing I check.

I think the mains are the next logical step unless somebody else comes up with a possibility that my rather limited intellect has failed to assess

John

[John A]

I think the mains are the next logical step unless somebody else comes up with a possibility that my rather limited intellect has failed to assess

John

Problem like this will sure make you question your intellect !  You'll find it,  it's the simplest engine out there but that doesn't mean it's easy to find the culprit !

[Chuck in Indiana]

Problem like this will sure make you question your intellect !  You'll find it,  it's the simplest engine out there but that doesn't mean it's easy to find the culprit !

True. A friend had an oil pressure issue with a 90 Continental, and eventually found it with a complete tear down. 

[Tom H]

I do not have an answer for you, but I thought some oil pressure numbers, at least from a Hydo may help.

Cold start and idle at about 1100, about 60psi
Cold and less than a mile at about 2500, about 65-70psi
Hot at about 3000 is about 50-55psi
Hot in city traffic at about 2000 is about 40psi
Hot in heavy traffic idle is about 5-10psi

This is with a cheap fleabay electric oil pressure gauge, so how accurate it is I don't know. The oil is 5w/40 syn. for the Hydro. Even when at idle hot, I have never had the idiot light come on.

Just a thought, could your idiot light sender be bad or the wrong one for the bike?

Good luck!
Tom

[Old Jock]

Thank you Tom your effort is much appreciated

The problem with the Hydro running oil of that viscosity & it probably has the 4 bar relief valve, which is borne out by the 60psi on start up, means the pressures I should see on the 1000 will be about a bar (14.5psi) higher

I'll find it, I'll probably pull the front mains out of curiosity, if nothing there put it back and then switch to assembling my 1100 which is in bits, but (hopefully) fixed from its crankcase pressurization. Never happy me it's either too much bloody pressure or not enough 

Then when the 1100 is all together transfer back to this bike, as I could be well into the summer before getting around to crabbing it

Many thanks to everybody all the comments are appreciated & give me some succor and pause for a lot of thought, as well as a sanity check which at one point I honestly thought I needed badly as I have to engines here with really oddball faults

Probably get them both sorted just in time to be too old to ride 'em

John

[jacksonracingcomau]

how much oil goes to cam gear tappets etc ?
apples pears etc
 compare hot at 8k then worry
just for ref Carrillo say 10psi per 1k revs, only figure I used racing

[Old Jock]

Hi Jacksonracing

I have no clue and you've reached my knowledge limit, about the flows and pressures inside the engine in detail. Even if I had I doubt I'd be able to instrument it to do any meaniingful comparison.

The only logical thing I think I can think of is slowly pull things apart looking for a likely culprit.

It should be pretty obvious I reckon, if a little sole destroying slowly pulling an engine apart and not finding anything.

When I do find something I'll be sure to post

John

[Frenchfrog]

You have all my empathy John...was at a similar point a few months ago with my t3 rebuild showing low pressure but eventually the penny dropped and I found the issue...now all is good.