[mesbenshade]

Well, I know that this winter will be time for a rebuild, but until then I'd like to keep her together for summer enjoyment! I am getting quite a bit of pressure and oil out of the vent tube at the rear of the block, especially at high RPM. Oil pressure is high when cold, but drops to 5-7 psi per 1,000 RPM when hot.

1) Potential diagnosis? ...or will I just need to wait until I tear the whole thing down?
2) As long as I'm keeping her full of oil, will I be doing to much harm to keep driving her through the season?

Thanks for your collective insight,
Mark

 

[alfazagato]

How high oil pressure when warm? How low when cold?

 

[mesbenshade]

When cold it idles at 50 psi, and with any revs pegs at 80 quickly. Once warm the pressure barely registers at idle, but comes up quickly with revs... say 15 psi at 2000, 25 at 4000, and 35 at 6000.

 

[gowanusvin]

Actually, given the vagaries of these gauges, these readings may well be normal. I'd suggest hooking up an external oil pressure testing device.

 

[mesbenshade]

Good call... I'll post the results. Quite honestly I'm more concerned about the amount of oil I'm losing at high RPM, is it normal to have dripping from the vent tube?

 

[pathung]

Not having driven any of my 750/101s yet, I couldn't comment on 1300/1600 engines, but in both of my 1750cc 105-series cars, 4000 rpm produced around 60 psi of oil pressure, while idle typically generated 30 or so psi. These are dash gauge readings, but since they are from two distinct cars/sets of gauges with strong engines, the results are probably believable. In other words, I'd be a bit worried if I were you, and prompted to conduct an accurate "external" reading of oil pressure asap.

 

[jburning17]

what I see

When cold it idles at 50 psi, and with any revs pegs at 80 quickly. Once warm the pressure barely registers at idle, but comes up quickly with revs... say 15 psi at 2000, 25 at 4000, and 35 at 6000.

On my '58 normale, I get something similar. I haven't checked the various pressures at all the rpm's, but I get about 50psi on the gauge at driving speed, and next to nothing at idle. The engine is pretty fresh, but I don't know if there is a new or rebuilt oil pump in there. The pressures are higher when cold. I don't recall how much higher, but not the 80 psi that you see--a 15psi bump throughout the ranges is probably what I am getting.

Jon

 

[mesbenshade]

Thanks Jon. Do you notice a high level of pressure and any oil escaping from the vent tube at the back of the block? I have what I can best describe as exhaust mixed with oil escaping pretty steadily.

 

[jburning17]

Thanks Jon. Do you notice a high level of pressure and any oil escaping from the vent tube at the back of the block? I have what I can best describe as exhaust mixed with oil escaping pretty steadily.

Nope, I don't see anything like that. I only get the mandatory couple of drops from a couple of spots after every drive. But that is all it is.

Jon

 

[Gordon Raymond]

Exactly when is "rebuild time"?

If it's blowing oil out the breather, you probably have considerable blow by past the rings and valve guides. If your pressure readings are accurate, the bearings and / or oil pump are on the way out too. How much (miles - + high rpm) do you plan to drive before winter? When does anyone start on a rebuild that could be extensive? How do you feel about grinding crankshaft journals way undersize, if it's currently eating itself up? How long will it take you to find all the bits you need for the rebuild? Lots of these questions you will have to answer for yourself, enjoyment now, vs time and $ spent later. Last year I watched as a fellow drove his 1600 abnormale, with brass showing on the mains and rod bearings, blowing oil like a gusher, low oil pressure ALL the time, + 2 broken engine mounts and a leaky rear seal. He usually shifted somewhere beyond 6500. By some hand of fate, the poor thing stayed together until "winter". His bill for the rebuild, however, was considerable. It's all up to you. To quote Clint Eastwood, "Do you feel lucky?" Hope this helps. Gordon Raymond

 

[mesbenshade]

You know Gordon, you're a real light in my day ... but I can't thank you enough for the reply!

So, I'm going to need to do a bit more investigation before rolling the dice and sacrificing a goat to the ghost of Nicola. True oil pressure readings that Patrick suggested and a compression test are in order. Maybe even pull the oil pan and see what I can see?

Either way, sounds like I'll have some interesting pictures of engine guts to post!

 

[Gordon Raymond]

Investigation will reveal the best and worst, AND make your decision MUCH easier, and one you can live with!
The photos will be great, and help others here on the BB as well! Thanks!

Best, Gordon Raymond

 

[Brad Baum]

Mark,
I would say Gordons insight is technically very good, and full of wisdom. My only fault with his input is he is to gentle. If it were mine, I would not run this engine any more untill your prepared to do a full, high quality engine rebuild. Your jewel is worn out.
Brad Baum

 

[alfazagato]

You might find a cylinder leakage test useful too as it helps you to pinpoint the leaks. As Gordon says the more you know....