Oil pressure questions....

[Doc in AZ]

ok, so this is a novel of a post, i'm hoping you guys will read it through and let me know what you think.

i've been working on my old econoline with a 200 I6 from a 65 falcon, we think. internal specs are unknown aside from how nice and fresh everything looked when we pulled the valve cover. no build up inside the head, always cranked right up and shut down immediately when i turned off the key. unlike a lot of the older motors i deal with that just kind of spool down when you turn off the key due to low compression.

we are finally out of the 110*+ weather here in Phoenix, AZ. and i have fought all summer to keep this thing from getting too hot. but a couple weeks ago something went wrong.

here's where i'm at with things...

rebuilt radiator - 3 core brass
new water pump
192* thermostat
15w40 rotella oil
DSII distributor
MSD 6AL
stock plugs @ stock gap
stock 1BBL carb

it seems to run about 100-110* over ambient air temps. so on days it was 115* going 55mph on the interstate my temp gauge (aftermarket with numbered graduation not just hot and cold range) would start getting above 220* and i would have to get off the freeway. gearing is set up to run 55mph @ 2500 RPM and 70mph @ 3000 rpm.

a couple weeks ago on my way home in the evening (over night lows of 95* yuck!) and temp gauge was steady about 205* then the bus started feeling a little sluggish & the temp gauge started rising, lost more power, started pinging on acceleration and the engine started rattling pretty loudly.

clutch in - check. put it in neutral - check. turn off key - check. call the tower and have them clear the runway for emergency auto-rotation landing with emergency crews standing by... lol... actually, just coast to the next exit and see what happened.

i thought maybe i blew a hose or something and it got hot faster than the gauge could report it. there was nothing visibly wrong with the engine. oil was maybe a pint low, radiator had water, nothing leaking, steaming or smoking. hmmmmm. after about 10 minutes i decided to hit the key and see if it would even turn over. much to my surprise it started right up. it sounded a lot like my old 12V cummins but wasn't smoking or anything. i was about 2 miles from the house and figured i would drive it and see what happened... if it blew i'd rebuild it, if it didn't i'd keep driving it.

i got on the frontage road and made my way up to about 40mph and let it coast with the engine running to keep air moving over the engine and radiator and it was running at 200* and quieting down. by the time i got home it sounded like it normally would after a 20 mile drive on the freeway.

i expected it to be locked up when i went to start it the next morning but it cranked right up and sounded fine. i was driving it to my shop to work on it but only made it about 5 miles when it started getting loud again so i pulled off and called a wrecker... those guys at USAA road-side assistance know me by name now... lol. once i got it back home i ran through the valves and found a bent push rod on #4 cylinder. it was bent enough to rub the engine block but was still traveling up and down and working the rocker. it looked like it had been that way for a while and the valve was correctly adjusted to the bent push rod. i checked the valve operation and it seems to move freely not like it was bent and wedging it's self in the guide. i straightened the push rod and put it all back together.

once i got it running again it was puffing a little smoke from the breather but not bad, and if i revved it real quick it would puff a little blue smoke out the tail pipe... meh, looks like the rings collapsed a little. but above 2000 rpm it starts dripping oil out of the breather on top of the valve cover... yup, looks like blow-by.

ok, so enough history, here's the problem.

i connected the aftermarket oil pressure gauge yesterday to see what was going on, i ran the motor to bleed the supply line before i tightened it down at the gauge.

oil pressure at idle (650rpm) with engine at 180* is about 35psi, it only goes up to about 45psi at 3000 rpm and that seems ok to me. but any time i run on the freeway (55mph @ 2500rpm) it doesn't take long before you see the oil pressure gauge start to drop off and hear the rods & valves start to complain. it drops slowly at first down to about 30psi then it starts to drop a little quicker and will go as low as 10psi before i push in the clutch. i have never had the factory oil light come on when this happens and it has a brand new sending unit for the idiot light.

the first time i saw this i got real nervous and put in the clutch and watched the gauge while i had my finger on speed dial for the tow truck. at an idle, coasting down the freeway, it stayed about 10psi for a second or two, wiggled a little then jumped right back up to 45psi and the engine sounded happy again.

i drove another mile, saw the same thing, i did the same thing, the engine did the same thing. hmmmmmm. so in the interest of trouble shooting i just stayed on the freeway and tried different things.

this is the final analysis... at a steady speed on flat and level ground cruising down the freeway, when the oil pressure starts to go down, i leave it in gear and just let off the gas and before i can count to three (one potato - two potato - three.... oh, there's the oil pressure) it's back where it should be. it also has a slight miss under acceleration, no so much one that you feel, but you can hear it if you are driving next to a wall, but otherwise it's a smooth idle and quiet cruise. so now the engine water temp is much more stable (at thermostat temp of 192*) where as before it would stay about 200-205* even in 110*+ heat then after about 5 minutes on the freeway it would start rising real quick til i got to 220 and i would have to get off the fwy.

i have a few ideas what it might be but am interested in hearing other suggestions based on first hand experience / knowledge.

- broken/loose/damaged oil pump pick up tube
- old and worn oil pump that is cavitating or losing pressure at higher rpm
- worn rod or main bearing that is allowing oil to "flow" rather than maintain "pressure" with a tight factory tolerance
- oil is not making it back down to the oil pan quickly enough to maintain pressure but letting off the gas for a three-count is long enough for it to drain back down

thanks for looking

-doc

 

[Does10s]

My guess......pick up screen is plugged, or pick up tube has a leak somewhere. So it's sucking air at higher RPMs.

Will

 

[Doc in AZ]

great info, i didn't know there was a screen in there, certainly not the first engine i've played with, but my first ford six and i haven't torn one apart yet.

looks like i'll be rolling it in the shop this morning and dropping the pan...

 

[mysavioreigns]

I thought the same thing does10s said, before I saw his response, so I would check that.

Good luck

 

[Doc in AZ]

good call guys, i was wondering about the oil pressure before, thinking maybe it was slowing down and friction was causing the overheating but never really had much time to deal with it... that's the problem with having a shop... always working on someone else's stuff. the old saying is true "it's the cobbler's kids that go without shoes".

so i popped the pan off and saw the mess on the screen and when i pulled the pick up tube nothing was dripping out of it so i thought it was done draining. much to my surprise it was full but so clogged it wouldn't drain back to the pan. and from all work i've done to this thing i already knew the PO had a love affair with RTV and lived by the motto "if a little is good then MORE IS BETTER!!". there were big chunks of silicone in there too, stuck between the screen and the strip of sheet metal that presses against it.

here's what i found - you can click on it for a larger image



thanx again, i really appreciate the help!

cheers
doc

 

[Explorer]

Yeah, that's not good. On a side note, you mentioned oil light didn't come on, all it takes is 5psi to keep that light off. By that time, damage is already occuring. I'd change that permanetly to mechanical gauge.

 

[Doc in AZ]

once i had it running it sounded so smooth and quiet... it purred like a kitten. i sat there at an idle watching the oil pressure gauge stay right about 45 even as the temp gauge reached 180* it was steady at 45 and would go up to almost 60psi at 3000rpm. it even seemed like it was smoking less out of the breather.

as i headed home down the interstate at 55mph it sat right about 50psi or so and i was sure that all was right in the world again... but... a couple minutes later the pressure gauge started dropping again... not to the extent it was yesterday, but still starting to go down to about 20psi driving at 2500 rpm.

so now i'm thinking that i have a real bad crank bearing or something that isn't holding pressure or i have a faulty gauge.

keep in mind i'm working on an econoline. you sit above the steering tires and almost on top of the engine that is wedged between the seats. i used a mechanical oil pressure gauge that is mounted to the heater box so about level with the pedals. this is about 8-10 inches ABOVE the motor and the oil drains back into the engine when it's not running and the tube is nothing but air. could that be giving erroneous readings? should it not be able to drain back down by maintaining it's own "vacuum" inside the tube?

you can see pix of it here http://www.facebook.com/media/set/?set= ... 010&type=1

 

[Explorer]

Air in line to oil pressure gauge is not an issue.

 

[Does10s]

While you dropped the pan, did you happen to pull the oil pump? If stuff is stuck in the pickup screen, then there a very good chance that little bit smaller stuff went thru the screen and into the pump....then of course into the main bearings.
If I recall the tolerence between the pump rotor and housing is suppose to be <.006" with .002" being ideal. Although I don't exactly remember off hand. I have all this stuff written at home!

Also the main bearings can be replaced while the crank is still installed and the motor in the truck. The hardest one is the rear main of course, but still doable.
And......check the rod bearing too if the mains are junk.

Later,
Will

 

[Doc in AZ]

if i had a little more time i would have dropped the oil pump but was in a hurry and the clogged screen seemed like the glaringly obvious problem. as i cleaned it i had "pull the oil pump" coming from the angel on my shoulder and "screw it, we're short on time, this is the problem right here!" coming from the devil on the other shoulder.

after driving about 80 miles this morning i think i can say that it's not rods or mains. i let it get low on oil pressure a couple times and finally heard the noise i heard the first time that made me think i spun a bearing. the noise is all in the head, like valve train noise. this is the first motor i've had with hydraulic tappets so bear with me because i have only speculation. it seems like maybe when it got low on oil pressure a lifter failed to pump up at all & the others sounded like it need a valve adjustment. 10 minutes later when i came out of the house it sounded just fine.

one thing i noticed when i had the oil pan off was the timing chain. it was really sloppy. i pushed it with my finger and it had about a 1/2" of sad to it, from where it was hanging to pushing it up and making it tight. while i'm not familiar with this specific engine, i know that's not a good thing... lol. aside from valve timing issues (which explains why my ignition timing has been such a beotch to nail down) would this cause any problems with the oiling? i know it drives from the bottom side of the dizzy and the rod looked good when i pulled it out when i did the DSII swap.

the problem has gotten progressively worse since i cleaned the screen yesterday. i tried to get some video of what it's doing but what should have been the best, of course, didn't record. but you will see it hovering about 25psi @ 55mph / 2500rpm. it goes up and down a little bit as i play with the throttle and when it dips all the way down is when i let off the throttle completely then you will see it gradually rise back up while still coasting then it stays put. it will do it at any speed but obviously the higher rpm causes it to happen much more quickly. at 40mph it will take a few miles at a steady speed to see it but at 70mph it happens as soon as you let off the throttle from acceleration to cruise.

http://www.youtube.com/watch?v=TVahJXQslPc

i'm guessing now that it's more crap that clogged up the screen because it was perfect yesterday for about 10 miles on the fwy. now it's got a much lower idle pressure (even cold) and it takes a dive towards zero much more quickly... i'll certainly be pulling the oil pump this time.

 

[bubba22349]

Oil pump could be weak, and than the oil passages can have sludge built up and sounds like it's probally a high mile engine so bearings can be on the loose side too. You can clean and change out the parts but than with the timing chain being loose might soon be the time to rebuild the bottom end

 

[Doc in AZ]

yeah, i know it's tired, i was just hoping to nurse it along a little more. i just found another 200 complete air filter to oil pan and it's a runner so i'll have to make the time to do a swap.

anyone ever take an engine out of an early econoline 61-67? i will either have to gut the interior, disassemble the dog house and bring the cherry picker in through the side doors or unbolt the front axle & out-riggers and drop it out the bottom then lift the bus up over the motor like a volkswagen.

 

[bubba22349]

You could also try some engine flush to clean out the oil passages to help it run a little better. I use to use the Justice Brother's engine flush and it worked great, was talking with my brother in-law the other day he lives in the Phoenix area he said that they now had JB products near him.

On swapping out the engine I have done a number of those old vans, I use to pull the passenger seat and unhook the door stop (door opens all the way flat) remove the engine cover etc. than use the cherry picker to pull it out the door. In some ways they are very easy to work on and much faster to do than a pickup or car.

 

[Doc in AZ]

i've had the bus parked for the last week or so waiting for the time and opportunity to pick up another motor from a guy on the other side of town. i went and looked at the motor and it's complete except for the air cleaner and has been sitting outside semi-covered. it's worth the $100 he's asking just for parts, but after seeing it's been sitting out i'm thinking it's not the best candidate for a bolt-in-and-go type of thing.

kind of sad when i'm almost 40 & i have 4 cars and none of which are in a streetable condition (2 early econolines, 05 jeep tj rock crawler, 53 cj3b rat rod roadster) so i borrowed my dads neglected 95 ranger with over 200k miles on it. the 50 year old interior in my econoline is more comfortable and enough motivation to crawl under it in 105* heat.

i pulled the oil pan again and took the oil pump off. the screen was clear so that was good news. when i took the oil pump apart i found a little dished button/cap thing that should go in the hole of the oil pump drive gear just floating around in the middle rather than capping off the hole where the drive shaft comes in from the top. i'm guessing i've found my problem with the mysterious oil pressure loss.

i haven't found any good schematics of the oil path through the block, but i'm guessing that it's either losing suction because of cavitation or directing it up through that hole rather than through the correct path to the bearings. also guessing that letting off the throttle is enough to let it jiggle around a bit and pick up a little oil pressure.

this looks like it's a relatively new melling pump and it looks like when i was trying to seat the distributor i knocked this little cap loose. has anyone got a picture of where it should be inside this gear? i was thinking i could just drop it in there and then with a socket on one side of it and a punch through the other side where the drive shaft drops in i could just dimple it back in place and fuse it in place with the TIG welder.

anyone have a good reason why this wouldn't work? i just want to make sure i put it in the right place first.

 

[woodbutcher]

Hi Doc.IIRC,does`nt the oil path from the pump go to the filter before the engine?If I`m wrong,someone please correct me as I`m always open to learning more.
Good luck.Have fun.Be safe.
Leo