(quoted from post at 08:25:20 08/01/18)
(quoted from post at 22:17:05 07/31/18)
(quoted from post at 18:41:34 07/31/18) Priming the system on a fresh build is a good idea because it contains no oil. Priming an already-run engine is not necessary because the components are already oiled. Even though most of the oil drains back into the pan the surfaces retain a layer of oil. Unless the engine sits for a long time without being run I wouldn't bother. Just my $.02.
Most of my older Chevy trucks have a slight knock on start up for the first few seconds and have for years , still run great . My 3 cylinder Ford diesel will be expensive to rebuild and the N's have their oil pumps above the oil level . I see 12v gear driven oil pumps for about $40 . Just wondering if anyone has first hand experience with pre oilers , factory or aftermarket . Whether its practical or not is the other side of the coin . Spending $4k restoring an 8N is not practical but if a man wants to do it I'd say go for it . Always glad to hear pro's and con's on any subject here .
Practical in that it can be done at a reasonable cost? Yes.
Practical in that it will buy you measurable improvement in service life on any of these engines? Doubtful.
I have no personal experience with pre-oilers but here is my basis for saying that:
Most main/rod bearing wear occurs on startup and shutdown when the crankshaft is spinning at very low RPM and the hydrodynamic oil film that keeps the journal off the bearing surface becomes so weak/thin that you get metal to metal contact. Pre-oiling will do nothing to prevent that. It will however ensure that there is sufficient volume of oil in the journal oil oil clearance at startup to allow the oil film to form quickly once the crankshaft RPM comes up to speed. If bearing oil clearances are already tight preventing excessive drain back and oil pump delivery is timely the gain from pre-oiling is minimal. If bearing clearances are wide and/or oil pump delivery is delayed the oil delivered by the pre-oiler is simply going to disappear under load and the oil film will be lost until the oil pump delivery catches up.
In summary if the oil pump delivery is not nearly instantaneous the initial gain from the pre-oiling is insignificant compared to the wear caused by the delay coming from the pump. And in no case does it eliminate that startup/shutdown window where the journal is in contact with the bearing and the bulk of bearing wear occurs.
TOH