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1991 351W E4OD
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Discussion Starter #1
A couple things I'm trying to wrap up on this new engine I built.

Refer to this thread to see what's been done to my new engine: New 351w Rebuild; Idle/Power Issues

1991 351w E4OD

The engine itself is running pretty good. Just a couple things I need another opinion on.

I noticed the lifters were sounding a little noisier than they should so I hooked up a mechanical gauge to the sender hole and I'm not too crazy about the readings.

At cold start it's only at 10psi then when it warms up it drops to 3psi. If I rev the engine to like 2,500rpms it'll come up to mid 20s, but then back down to 3psi at hot idle. I checked the oil pump shaft to make sure it was in correctly, and even running a drill on it only brought it up to 10psi.

I used a Melling M83 oil pump that was basically new and was working great when I had it in my stroker engine. But now I'm wondering if it's on its way out. I'm dumb and probably should've just installed a new one off the bat.

I plastigauged all my bearings when I built the engine, and I even just changed the oil yesterday to look for any metal; clean as a whistle. Even put some Lucas oil stabilizer in there with the new oil, but no improvement. I know it's probably going to be a pain, but should I drop the oil pan and try a new pump? Don't know what else the problem could be. If yes, what oil pumps is everyone having good luck with? Definitely not a job I'd want to do twice with the engine in the truck.

The other thing is when I took the truck for a little test drive it seems like I'm having a transmission issue, like maybe it's starting out in a higher gear or something. Acceleration is just way slower than it should be, and even mashing the pedal all the way to the floor doesn't change much. It just gradually picks up speed. I mean, I know these trucks are not race cars, especially mine with the 35s and stock gearing, but I know it wasn't this bad.

I had installed an aftermarket TPS from the parts store when I was having idle issues in the beginning so I checked that first. Voltage seems good (0.93-4.65v) and has a smooth transition as you open the throttle. When I check resistance though there seems to be a dead spot around 700ohms, which is close to wot; my meter just cuts out at that spot every time. So I definitely think I should replace that with a Motorcraft this time.

My transmission fluid level is good, but the truck has basically been sitting for the past 10+ years so I'm wondering if maybe the valves are sticking too or something. I haven't done a fluid change yet, but think it's probably a good idea. Just was hoping I wouldn't have to do that yet until I was ready to buy an aftermarket valve body. The oil, filter and gasket is like $150 itself.

Other than those two things the engine sounds healthy so just wanted to throw these ideas at you guys and see if any of you concur. Or maybe got some ideas of your own for things I should check?

Thanks in advance! :)
 

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def start with the pump. that low of oil pressure has to be due to pump or filter. what filter did you go with?
 

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1991 351W E4OD
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Discussion Starter #3
def start with the pump. that low of oil pressure has to be due to pump or filter. what filter did you go with?
Yeah, the more I think about it the more I'm leaning towards just throwing in a new pump.

But that's a thought. I didn't even think of what effect the filter might have on the oil pressure. The oil filter I have on there is a WIX 51515. I don't know too much about their reputation, but I was just trying to stay away from the cheaper brands like Fram.
 

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1982 FSB 302, c6, NP208 manual, manual hubs, manual windows, 3.00 gears LSD rear, 235/75/15 HK ATM
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Yeah, the more I think about it the more I'm leaning towards just throwing in a new pump.

But that's a thought. I didn't even think of what effect the filter might have on the oil pressure. The oil filter I have on there is a WIX 51515. I don't know too much about their reputation, but I was just trying to stay away from the cheaper brands like Fram.
I haven't ever had bad luck with wix products. I second the new pump. The only other thing I could think of is if your pickup tube didn't get a good seal at the pump and it is sucking air from the top of the pan with what oil it can get through the pickup.
 

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Yeah, the more I think about it the more I'm leaning towards just throwing in a new pump.

But that's a thought. I didn't even think of what effect the filter might have on the oil pressure. The oil filter I have on there is a WIX 51515. I don't know too much about their reputation, but I was just trying to stay away from the cheaper brands like Fram.
anything is better than a fram. letting the oil just poor onto the ground is probably better than running a fram.
 

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I run Wix filters exclusively on everything. Back in the early 1990’s we cut up some Wix and Motorcraft , And Fran filters. Back then Wix was claiming 25% more filtration on the oil filter than the stock Motocraft.. I wish I had pictures of the three side by side, the difference would blow you away... we also put 1 Tablespoon of silicon sand into a gallon of oil and poured through each filter (1 gallon of 10w30 mixed with sand for each filter for a total of 3 gallons of mix). The Fram filter recovered very close to 1/3 of the sand, Motocraft got most of it (about 1/4 teaspoon in the bottom of the filtered jug) while the Wix caught all of the sand (no sand particles left in the oil). We then decided to flow the other two jugs of oil through the wix filter, we ended up with 2.5 tablespoons of sand in the filter, and none in the jug... but the filter plugged up with that much sand... but hey, that’s what a filter is supposed to do.
 

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Discussion Starter #7
I haven't ever had bad luck with wix products. I second the new pump. The only other thing I could think of is if your pickup tube didn't get a good seal at the pump and it is sucking air from the top of the pan with what oil it can get through the pickup.
Thanks, good to know about WIX. I was pretty anal about assembling this engine so I think I put the pickup on right; new gasket and all. Could be wrong though, and maybe it could've still managed an air leak. lol But I figure if I'm gonna drop the pan then might as well have another oil pump waiting to throw in. A new Melling M83 is only $40 or so. Definitely going to pick one up.

anything is better than a fram. letting the oil just poor onto the ground is probably better than running a fram.
:ROFLMAO: I'd say you're being melodramatic, but I'm sure it's the truth.

I run Wix filters exclusively on everything. Back in the early 1990’s we cut up some Wix and Motorcraft , And Fran filters. Back then Wix was claiming 25% more filtration on the oil filter than the stock Motocraft.. I wish I had pictures of the three side by side, the difference would blow you away... we also put 1 Tablespoon of silicon sand into a gallon of oil and poured through each filter (1 gallon of 10w30 mixed with sand for each filter for a total of 3 gallons of mix). The Fram filter recovered very close to 1/3 of the sand, Motocraft got most of it (about 1/4 teaspoon in the bottom of the filtered jug) while the Wix caught all of the sand (no sand particles left in the oil). We then decided to flow the other two jugs of oil through the wix filter, we ended up with 2.5 tablespoons of sand in the filter, and none in the jug... but the filter plugged up with that much sand... but hey, that’s what a filter is supposed to do.
That's a neat story! I'd have been very interested to see those pictures. Definitely feeling secure with my WIX filter choice now. :)


Thanks guys! Got a new Melling M83 on my shopping list along with the Motorcraft TPS. I'm also going to throw some Lucas Trans Fix into my transmission and see if that frees anything up. Worth a shot.

Man, I cannot wait to drive my Bronco again. It's been a very long time. PNO since 2007. Well I guess I can at least claim it as a low mileage Bronco with only 154k on the clock. lol
 

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1991 351W E4OD
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Discussion Starter #8
Hmm, after reading a little more maybe I'll hold off on putting in that Trans Fix goop. The Bronco has yet to throw any transmission codes, but maybe I should give the wiring a look over first.

It feels like it's starting in 3rd maybe, and I did get it to shift up a gear from there, but that was it. If it was in limp mode it would be stuck in just one gear, right (4th?)?
 
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