How far down the rabbit hole? 4.0 engine OHV

[Tedybear]

Okay here goes:

Bronco II is slowly on the way out. The engine is tired and I decided it might be wise to invest into something a few years newer, and with 4wd and a 5 speed manual.

Yep, I did an El' Dummoooo. Picked up a 1995 Explorer Sport. Fair condition, but the seller scammed big time. Heard it run and did sound okay. Even with very high miles the engine sounded great.

Picked it up and brought it back home to work on it. First thing: Oil change, thermostat & cooling system service. Oil came out like a straight 50w. Oil changed to 10w30, motor craft filter. Started it up and it was running like a top.

Let it run a little longer to purge out the air, and then the knock started.

https://youtu.be/UTfto1dtgQk

Looks like this winner of a seller had it loaded with crazy thick oil to mask it.

It also looks like the best cost effective option is going to be me replacing this engine with one from a salvage yard. Now given this is a manual transmission I have concerns about the pilot bushing/bearing. On a 1995 4.0 engine. Is that built into the flywheel or crank? Most likely the replacement will come from an automatic. So I'll need to drop in a new pilot bearing.

Currently I'm looking for options. I know this isn't an forum for explorer. However I know quite a few do conversions over to 4.0's. I'll be doing more on this in the later afternoon tomorrow. Hooking a real oil pressure gauge onto it and seeing what the results are. Then hopefully find out how far down this rabbit hole I'll need to go through.

Options, ideas on that sound... Pretty much interested in how badly screwed up this whole project is.

S-

 

[cdxhizors]

On my 97 the pilot bearing was built into the flywheel. Sorry to hear about the craigslist scam!

 

[Tedybear]

On my 97 the pilot bearing was built into the flywheel. Sorry to hear about the craigslist scam!

It was pretty upsetting. On the lighter side the frame and body in general isn't bad on the explorer. Rockers and a part of the rear lift hatch needs replacement.

Hope that's right about the pilot on the 95's and 96's. I've replaced auto transmissions before (3 times in the Bronco alone) But never had to do an engine swap sense my college days 25 years ago LOL.

Any tips or ideas will be welcome on that front!! (I love a good adventure)

I knew something was wrong when the oil drained out like a 50w was put in. I'll be hitting Napa on the way to work to get another hose kit for my oil pressure gauge. I saved the old one from my Bronco II when I changed it. I had to use the hose it came with to fix a leaky fitting. I have a transmission oil pressure gauge by MAC tools in the barn I work out of. (lost the house finally it was sold. Nice single car garage with a lot of space... So I'm back in a barn to work)

Report back this afternoon or early this evening once I get the pressure readings. But I think it will be a forgone conclusion.

No one has shown any interest in picking this up as a project, even at a loss from what I paid for it. Looks like I'm stuck fixing it or scrapping it. If I can secure a decent engine for 200-300 bucks, I'll spring for a cherry picker and change it myself. As I told the wife. We just got shoved a whole bunch of lemons. Time to get squeezing for some Lemonaid.

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[bronco2fan]

Yeah, sounds like someone wasn't very honest at all. Imagine that on CL. Good news is that the swap is very easy with the same motor, all plug and play really. You just have to find one that's in good shape. Or if you're serious about keeping it and wheeling, rebuild that one? Lots of good info here to help you out. Good luck and keep us informed.

 

[Denisefwd93]

I'd go a bit deeper then just listening. They tell me these V6's go for 300 plus

 

[cdxhizors]

They go for 300 plus taken care of. Pulling the motor is very easy.. If you keep the exhaust manifolds attached to the motor. Just break it apart at the y pipe. Replace those stupid studs with a few bolts and nuts. This avoids snapping manifold bolts into the head. Remove the radiator for plenty of clearance. I'd even remove the harmonic balancer. Upper intake and fuel rail removal makes it very easy. Leaving the fuel lines attached and putting it to the side. Remove the a/c and alternator.. Unbolt both accessory mounts from the heads(there's a bolt behind the belt tensioner so it has to be removed). Another tip is that bell housing bolts have different sizes but it's not possible to use the shorter ones in place of the long one so its self explanatory when re-assembling. Watch the oil filter housing on the passenger side.. It can get caught under the frame rail. Oh and the motor mounts have a single nut on top of a plate. Lift points I used were a single bell housing bolt on the back top, and another on the front of the head catty-corner from the back bolt.

Sorry for the long run on post but I removed a motor this morning in my 97 for the second time lol.

 

[Tedybear]

This just got a lot more interesting.


Did an oil pressure check. Stone cold we get about 65psi. All warmed up and at low idle we get about 28-32. Highly responsive to throttle position.

https://youtu.be/9ba2-bFCZ1o

We did a couple more videos of that noise.

https://youtu.be/c1U0dEQuZqs

https://youtu.be/khX22OePZfg

Here's where things get interesting. You can clearly hear the 'knock'. Upon giving it some gas, the knock diminishes to the point it's pretty well gone. Last time I had an issue with rod knock, it got louder and more pronounced when the engine RPM was raised.

Now where this blows my mind away....

I used a mechanics Stethoscope. I had that probe end all over the engine and transmission...and bell housing. NOTHING to report!! With that knocking sound? No place I touched the probe reported anything. The oil pan? I could hear rotational sounds, and even the 'Wshoosssssh' sound (best way to describe it) of the oil pickup! But no knocking sound.

Then I touched the probe to the exhaust pipes.

Bingo...... not as loud as I expected, but it's clear as day. I then probed higher up to the manifolds. The noise isn't "Loud" or as loud as what I'm hearing, but it's very pronounced and the only place I could pick up that noise was when I had the probe of that stethoscope touching the manifolds and exhaust pipes.

Possible burnt exhaust valve? I'm guessing on this. I've heard rod knocks before, and they always get much worse with acceleration and they are clearly able to be heard with the stethoscope through the oil pan. The fact when it's making this noise, I can hear all the "Rotational" sounds within the oil pan---and no knocking noise when I have that stethoscope touching various parts of that oil pan.

This isn't a rod knock that I know of....

Any ideas? Am I totally off base with the idea of a burnt exhaust valve?

S-

 

[aspevacek]

May want to get you hands on an inspection scope and pull the plugs and take a look in the passenger side cylinders to look for carbon build up on the piston tops. I had heard reports of it sounding like marbles on some engines when the carbon build up was present. One thing that does not make sense was the fact thicker oil masked the sound which would lead to think it was in the lower end.

Have not looked at the specs but the oil pressure sounds like it is about in line and acting like it should if there are not excessive gaps in the bearings and surfaces.

 

[Tedybear]

May want to get you hands on an inspection scope and pull the plugs and take a look in the passenger side cylinders to look for carbon build up on the piston tops. I had heard reports of it sounding like marbles on some engines when the carbon build up was present. One thing that does not make sense was the fact thicker oil masked the sound which would lead to think it was in the lower end.

Have not looked at the specs but the oil pressure sounds like it is about in line and acting like it should if there are not excessive gaps in the bearings and surfaces.

Given how wicked thick that oil was when it came out. I think, sense I've probed the bottom 1/2 of that engine and came up with a goose-egg for the source of that noise. This guy was a self proclaimed "DYI" type. I'm more likely to suspect that maybe he dumped in extra thick oil to mask what he thought was a rod knock. Why that noise didn't present itself during the initial inspection and when I picked it up, and had to drive it onto a car hauler? That's what has me scratching the noggin. The noise started up about 10 minutes into purging the air from the cooling system, after the oil change.....

After spending about 30 minutes crawling under this with the mechanics "ear" probing every metal cover? That noise isn't coming off the crank or connecting rods.

Heck, I wish my BII had that good of oil pressure. (It starts out at 60 and after driving and just sitting at a traffic light it can barely move the SunTune oil pressure gauge I installed years ago. It's likely about 7-9lbs just enough not to trip the idiot 'gauge' on the dash)

Looking at probing the upper half of the engine probably on Tuesday to check for any upper half of the engine sources of that noise. Seems this noise could telegraph itself from one part and simulate what seemed like a rod knock-- So what's next?

Probe upper half with the mechanics ear.
Use the scope on a rope (test light) to kill each cyc and see if I can pinpoint that way, which cyc is associated with this.
Compression test
Leak down test if suspect a valve issue. (Okay, I'm also looking for the excuse to pick up a newer air compressor. My step father killed the large one we have in the barn (scrap metal anyone?) And the backup compressor has pin hole leaks in the tank)

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[enjr44]

No real suggestions, except... An exhaust leak can cause a "knock" sound. I don't think "heavy" oil would cover it.

And, rod bearings get quiet under load and sound off when you let off. Mains get loud under load and quiet when you let off. That is until they are so bad they make noise all the time.

 

[gandrimp]

I have never seen oil pressure react that fast to throttle application.


Wonder if the noise is piston slap?

 

[Andy D]

Wrist pins make a racket. It happened to me in 2 different I 6s. Other than the noise, both engines ran well for yrs.

 

[AllanD]

God, some of you guys would go nuts If you had an original 289 Hi-Po engine...

They made the scariest set of noises, particularly if you didn't know what you were listening to...

But don't discount the noises that a cracked flex plate can make...

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