is it 120k, or 220k . . . or 320k?

A couple of years ago I bought a 1987 Dodge B250 which purportedly had 120,000 miles on it. After the first oil change, I disovered that my oil pressure was falling down to near zero at idle when the engine (a 360, btw),
is warmed up. Okay, so I change first the oil pump, then the sender, and finally the pressure gauge, with no change. Finally, I switch it to 15W50 oil, and the problem is solved -- presssure is up to 40 psi when running, and no lower than 20 at idle, from which we deduce that I need main bearings. So, my question is: should I take this as an indicator that this engine as gone around more than once? it seems to have lots of power, doesn't BURN any oil that I can detect -- I use the van infrequently, so it's difficult to say for certain, but it definitely doesn't smoke or do anythying that's in any way problematic. Is it worth putting in bearings, or would I be better advised to just get a low-mileage engine -- maybe even a 5.9 Magnum ;^)
I'd be inclined to just sell it, but it's really nicely equipped -- 360/727 torqueflite, limited slip rear, electric windows & door locks, factory interior, cruise control, tilt wheel , trailer towing package, heavy suspension. . . and everything even works!
What do you think? I've had many 100k+ vehicles, and have never seen bearings go in so short a time, which leads me to surmise that maybe it has a lot more than 120k on it.
Thanks.
Joe
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I might add that once a month I haul 40X50# bags of coal (1 ton) with it, and it handles it fine, takes hills like there's nothing in it at all, which seems to suggest that the compression is fine, though I haven't run a compression test. I guess that would probably be a reasonable diagnostic to try. . .
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Since the oil flow is from Mains to Rods, IMO you would have a problem with rods before mains. Not that the mains cannot be the problem, but I suspect not, if the rods are not rattling.
I'm more inclined to think that the cam bearings might be a problem. I have a 318 with the same symptoms you describe, and I changed all bottom end bearings. I also changed the oil pump, and none of this helped. I had tried heavier oil and nothing changed. This car now awaits a 360.
If the heavier oil has solved your problem, you should continue to use it. Meanwhile, you can build or acquire an engine that might be a bit better than what you have in terms of power. Changing bearings, especially cam bearings, in a van can be more of an adventure than simply pulling the engine and swapping in another.
If you decide to swap engines, I suggest power washing the underside and under the engine cover before starting, as this will reduce the amount of crud you have to deal with.
--
Max

Join www.devilbrad.com and find out what free exchange of info is all about.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

heavier oil to keep the pressure up. The 318 in my van has been that way since I installed it. I've put 80K on it without any problems.
beekeep
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks to all for the tips. Considering how little I use it, I'll probably just keep running it on heavy oil for a bit. Maybe if I get ambitious some day I'll put a 5.7 hemi in it 8^)
Joe
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Joe Befumo wrote:

on it. I have a 89 pickup that I replaced both the sender and the guage and it still showed low oil pressure. I installed a mechanical guage and the pressure is fine. I still have both guages in it. A lot of the time the electrical will show 20 pounds and the mechanical shows 60 right where it should be. I was told that those years had problems in that electrical circuit.
Grizz440
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks Grizz --
Actually, that was the second thing I did, right after the sender.
As it stands, I'll probably run it for a while just sticking with heavy oil, as someone else suggested. It pulls just fine, starts right up even in sub-zero weather, so . . .
At some point I'd probably want to change the timing chain, so then I might consider going a bit deeper and replacing cam, cam bearings & main & rod bearings, or I might just keep an eye out in the meantime for a low-mileage 360.
What i'd LOVE to do is put in a Cummins diesel or a 5.7 hemi, but I have a feeling that the first wouldn't fit (height), and the second would require all kinds of sensors that I won't have available, so a straight swap would probably afford me sufficient grief as it is.
thanks again,
Joe

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Joe Befumo wrote:

have the right idea. Run heavy oil until it starts hammering. I agree the Cummins would be sweet in there with the fuel prices the way they are. I like to use Lucas oil stabilizer in about everything I own. That may help you pressure problems too. It's hard telling about the miles on your van. It's easier to tell from the door hinges and interior then from the engine. The previous owner may not have kept the oil changed or used poor quality oil. I bought a pickup once that only had 30k on it. the lifters were collapsed from using poor oil.
Grizz440
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.