Oil pressure

[piit]

Hi, I would like to hear what are the typical oil pressures when engine in 80 and 100 celcius. Both with idle and approx 4000rpm.
-piit-

[alimey4u2]

64-71psi at 4000 RPM according to the manual. Mine is about 69 to 70. On idle it can drop a lot lower, without checking ( from memory) I would say about 20psi. I have a pressure gage mounted on the main gallery..

[piit]

Thanks!
I am asking because 1 wk ago I fitted the oil pressure gauge to solve my strange warm/hot engine "ever green" behaviour/sound and recognized quite low oil pressure.
Engine temp below 40 celcius pressures according to manual. Above 70celcius oil pressure starts to reduce heavily. In 70celcius 50psi, 80celcius 43psi and 100celcius 36-40psi.
At idle 14psi. These figures came after I added approx half liter STP to the engine (drained same amount from engine). Before that pressures were about 14psi lower except in idle.
Engine is oil leak free.

Seems that I have something to do before UK CBX Rally in August. To open crank cases is not problem, but what to check or what might cause low oil pressures with warm/hot engine.
Normally I would say check the oil pump and connecting rod bearings, but I have changed the primary chain 3 winters ago (approx 20000km ago) and checked those then.
What I did not changed because I could not find were the oil pump seal (I used liquid seal) and primary tensioner seals (yes they were hardened). Now tensioner seals are available from sixcenter.
I made visual checking on bearings and measured by "wire gauge" and were ok...did I use a correct word maybe not

Sirs, all support is more than welcome!
This wknd I will go to one Finnish rally and excepected to have 2000km on counter, so wish me luck
Next week planned to split engine.

Cheers,
Pete

[EMS]

Oil pressure is the result of flow and flow path diameters. An oil pump does not create pressure, it creates flow and that flow ,when pushed through given orifices or against resistance creates pressure. Oil pumps usually have a spring loaded check valve against which the output flow will exit the pump resulting in initial pressure. After that, the flow path determines what the pressure at any point in the system will be. Loss of flow due to internal leakage will result in low pressure.
If the gerotor set of the pump is worn and has too much internal leakage, flow will be low, resulting in low pressure. If the check valve spring is weak, the pressure will be low. If the following elements of the flow path have too much leakage/gaps (crank bearings) pressure will be low.

[alimey4u2]

Mike has covered this well, shell bearings oversized or relief valve lifting early/passing . If unsure, I would firstly check the oil pump screen in the sump.The tensioner is on the high volume low pressure cooler/ gearbox circuit so that wouldn't be in the picture...Two oil pumps/circuits don't forget...I have heard of a knackered pump but that is rare...

[piit]

Thanks! Valuable information to understand better the weak points! I do not have the Honda manual front of me to check can I remove the oil pump with splitting the crank cases.
The mentioned valve(s) are located to pump itself, right? What do you mean by gerotor, internal parts of the oil pump?
Sump screen is fine I check it twice per season, so I have done it once already.

Also I would like to understand the viscosity influence to oil pressure, as I wrote earlier below approx 40celcius the oil pressure is quite ok...I will follow-up this today.
I think this will disprove the knackered pump, but for sure to be investigated.

Anyhow, if I need to split the crank cases I will check the all possible bottle neck candidates and try to eliminate those e.g. tensioner seals etc.
Also bearings should be available in stock from DavidSilver...hopefully there will not be any probs to identify the correct bearings.
If I remember right inside the engine were some hand made marks, can you trust those markings or what method you have used?

Thanks,
Pete

[EMS]

Gerotor pumps are a common design for sump oil pumps for motor vehicles used both in engines and transmissions. Wear between the rotor tips and scroll as shown in this picture will result in a lack of sealing between the chambers, resulting in loss of flow.

[alimey4u2]

I think you can get to the pump via the sump plate, definitely the strainer...

Crankcase & crankshaft coding together with rods & colour coding on bearings should be reliable from factory assembly. It is always good to check with a micrometer just in case the crank has been reground... Always plastigage ( AKA wire gage) upon final assembly...

[piit]

Thank you Sirs!
I will update the status here next week.
Cheers,
Pete

[piit]

One q still, should the connecting rod bolt and nut replaced if removed?
-p-

[alimey4u2]

One q still, should the connecting rod bolt and nut replaced if removed?
-p-

Good question, all I can say is I didn't & I haven't had a problem at all, even though I have missed a gear once or twice & overreved the engine. . My engine develops more horsepower than stock....

Did I do wrong ? Have I been lucky ?? I too would be interested in the groups views on this...

[piit]

Jep, at least I have re-used the bolts and nuts once. Many times missed a gear between 1&2 in red line without problems.
Wondering now should I continue to reuse the same hw.

Cheers,
Petri

[alimey4u2]

Measure the length of the bolts & compare with new. See if there has been any stretch ? Or bite the bullet & fit anew. A thrown rod would be a lot more expensive than a few nuts & bolts...

[piit]

...for sure totally wrong place to start save money.
Does anyone know the length of new one?

[alimey4u2]

Can't help you there piit but I'm sure one of the guys will come along soon with the info...