Re: IML: Old Engines, Oil Pressure, Compression, Fun

["Rob van der Es" <R.vdes@xxxxxxxxxxxxxxx>]

Paul wrote: A low mileage engine destroyed by lack of maintenance  and 
incompetent repairs is one form of it that I find intolerable.



Very well written Paul !
Don't you just hate it to see those young kids with their souped up cars 
giving it full trottle after just firing up the engine.
If I tell those kids that it is important to warm up the engine and tranny 
first before going to WOT mode, they look at you as if you are from another 
planet..

One of them even had the nerve to say that this way of driving a car was for 
oldies like my 1960 Imp :)

Well at least "I" could hear their engines "cry".

I love to hear my big 413 running like the day it came from the factory !

Robert

----- Original Message ----- 
From: <randalpark@xxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Saturday, March 31, 2007 1:39 PM
Subject: Re: IML: Old Engines, Oil Pressure, Compression, Fun


> This leads to a sweeping statement and some general commentary.
>
> I find that the two most basic & revealing tests to determine wear on an 
> old engine are measuring the actual oil pressure, and checking 
> compression. Noise and smoke are pretty obvious, but they can be "covered 
> up". Sometimes they just don't occur in an engine needing major work. 
> Checking these two things on a seemingly good, warmed up engine is the 
> best way to tell if it's time for an overhaul.
>
> Worn rod bearings usually are the first major cause of low oil pressure in 
> a prematurely worn engine. Often this is due to incorrect fuel and/or 
> tuning which leads to pre-ignition, and extra pounding on the crank. I 
> have seen this happen in engines with less than 25,000 miles on them. 
> Premature top end engine failure is usually next, since most of the oil 
> flows the path of least resistance, it will go through the damaged 
> bearings, leaving the tight parts dry. All surfaces gradually wear, so in 
> high mileage engines, anything goes, including worn cam shaft bearings, 
> main bearings, and even the oil pump itself. Frequent oil changes/pcv 
> system checks are a critical part of good maintenance in order to maximize 
> engine life. This keeps oil passages clean, prevents clogs from sludge, 
> and the subsequent lack of lubrication to specific and otherwise long 
> lasting parts.
>
> Low compression can be caused by many different problems, but uniformly 
> low compression in a worn engine is normally caused by worn out rings. 
> Premature ring failure is often due to overheating. Poor tuning, improper 
> torquing of bolts, and lack of maintenance, such as leaky vacuum lines, 
> can lead to common non-uniform compression problems such as those 
> resulting from burned valves, cracked pistons, warped heads, and blown 
> head gaskets.
>
> All engines wear out and eventually need to be overhauled. I think that 
> there is value and merit in discussions about the causes and differences 
> between normal wear and premature wear. I also think it is useful to 
> distinguish between premature failure due to poor maintenance practices 
> vs. sub-standard design on the part of the manufacturer. Luckily, in most 
> cases, our cars well very well designed to begin with. Imperials from the 
> 1950's and '60s are among the very best American cars ever put on the 
> road.
>
> One of the most rewarding aspects of this hobby for me is maximizing 
> engine life. I have a great deal of respect for an old sweet running 
> engine that has been well maintained, with exceptionally high miles. I 
> despise waste. A low mileage engine destroyed by lack of maintenance and 
> incompetent repairs is one form of it that I find intolerable.
>
> Paul W.
> -----Original Message-----
> From: mikanlin62@xxxxxxxxxxx
> To: mailing-list@xxxxxxxxxxxxxxxx
> Sent: Fri, 30 Mar 2007 5:08 PM
> Subject: IML: Re : pressure vs volume
>
> This comes up all the time in various forms. Follow along....your oil pump 
> is a positive displacement pump meaning it can move a set amount of oil 
> each time it rotates, whether it is a spur gear style or a rotor style 
> like Chrysler uses. So for EXAMPLE, if it can displace an ounce of oil for 
> each revolution of the pump it will move 1000 ounces at 1000 engine rpm. 
> Now, if the various clearances in the engine bearings, crankshaft, 
> connecting rods, lifters, pushrods, let less oil past them than the pump 
> can move you will get pressure.
>
> If this doesnt seem clear, remember that we are talking FLOW here, and 
> resistance to FLOW causes PRESSURE. Dont think so..go turn on the garden 
> hose and let it run, youll see flow. Then put your finger over the end of 
> the hose and close it off about half way, you reduce the flow but increase 
> the pressure. Its not quite the same as the kind of flow vs pressure you 
> see in hydraulics where there isnt any leakage desired because in an 
> engine its a given that you will have oil leaking past the various 
> clearances in the engine, thats how it is designed. The oil cools as well 
> as lubricates.
>
> This is also why as an engine wears out the pressure will drop, because 
> the clearances get larger as the bearings and other surfaces wear. Since 
> the pump can still only move a set amount of oil, whatever that amount is, 
> the resistance to the flow of the oil lessens and the pressure drops 
> accordingly.
>
> Use a high volume pump as opposed to a high pressure pump. The only 
> difference between standard and high pressure is the relief spring and you 
> dont need higher pressure anyway. A high volume pump will give you more 
> than enough oil flow to create good oil pressure.
>
> Mikey
> 62 Crown Coupe
>
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