Engine knock and oil pressure

[Neal 97 250]

This car I picked up for free. It is in really good shape But I was told it had a knock so I towed it home. 1990 TownCar 302cid

So I removed the oil pressure sensor and put in a gauge in it's place. Then cranked it up. (Still has old oil in it ~1.5 years old, sat for a long time)

The pressure gauge was bouncing quite a bit (cheap gauge). But it went to between 20-35 psi when cold and at idle. Went to 25-35 when revved. I revved the engine up quite a bit trying to hear the knock. I could not hear it with just my ears. Didn't have any body to rev for me so I could listen with hose or stick.
So I let it warm up...

Now the oil pressure is between 4-8 psi at idle. Still no knock.
I rev it and pressure goes to 10 psi. Then I can hear a knock but only when I rev it pretty high does the knock sound off and only do I hear it as I let off the throttle then no knock as RPM's come down then it knocks some more when it reaches idle for a split second then no knock again at idle.

Basically it does not knock as RPM's go up or down just in between.

The knock sounds to me like it is from the bottom end. Sounds "loose" if you know what I mean. Deep thunk, clank, thunk then smooths out and no noise.

So I drain the oil. It is very thin but is not burnt. It has a Fram filter on it. My plans are to try and add 20W 50 oil and either a wix or motocraft filter.
Do you think this will "revive" it? I know some harm has come from the knock but since it doesn't knock when cold I am hoping the damage is minimal.

Also do you think the oil pump may be the cause of this issue as well?

I will change the oil and post an update.
Please give me your input and experiences and even suggestions as to what I can do.
Otherwise it is time to do a GT40p swap. LOL.


One more thing. This is the info I got from the guy who gave it to me:

New air suspension system installed Erwin Miller shop. Most engine work has been done by Miller. Front suspension has been rebuilt.
New timing chain, gaskets etc, new radiator, but Miller did not put on new pump which caused overheating problem and engine oil pump crash
Car has about 120,00mi
Car top is new 2006, done in Cinci $900
New tires 2008
I think the exhaust is new
Have replaced door electric window motors several times but they are a constant problem, issue with those years of Lincoln
Radio does not work well, wipers Ok, door locks Ok, trunk Ok, hood latch is problem have had it adjusted several times have to really push down to get it latched
Have had the steering gear box rebuilt in Cinci but is is leaking again. Power steering pump original.
Brakes should be new
Air conditioning has been converted to new Freon stuff. Worked well in Myrtle Beach
Has been sitting since spring 2008

Used to be my dads car. I have probably put $6000 in maintenance/repairs since owning it. Really a nice riding car. If I had a garage, I would have keep it going but, no time or place. Hope you can drive it.

[86VickyLX]

You got the lopo knock. If I were you, if you have the funds, I would rebuild the engine and get rid of that dumb cam it has in it. Go with something from a mustang, so it won't have that lopo knock. As long as the engine has oil pressure when its hot at idle, you'll be alright, but it will get worse as you drive it. If you're gonna put heads on it, you're probably gonna be romping on it, I wouldn't recommend a head swap on an engine that has low oil pressure/bearing knock, since it probably won't last much longer.

Good thing for you is, you have the lincoln logs. (1990 Town Car exhaust manifolds) These will fit the Gt40P heads without modifications. All you'll need are 2 90* spark plug boots on cylinders 5 and 6, and spark plug wire insulators on cylinders 5, 6, and 7.

[Neal 97 250]

I thought about a rebuild but I can get an engine for a very decent price but I am trying to see if I can avoid that for now.
If I have to I will replace the engine just trying to put that off unless absolutely necessary.
I believe I can get a 2000 GT40p for about $600.00 from an Explorer.

I got the car for free. Had to buy wasp spray and mouse traps. Then took the 3 year old dead battery back and got money back from that. So to date I have gotten paid about $55 for taking the car. I would like to see how frugal I can be for now with it and it still run decent.
Yes I will end up pulling the engine and doing an Explorer swap for sure but like I said for now I would like to avoid that if entirely possible.LOL

[grandpaslincoln]

The engine will run forever on almost no oil pressure and the knocking lower end. Drive it until it don't drive no more.

[gadget73]

The engine will run forever on almost no oil pressure and the knocking lower end. Drive it until it don't drive no more.

This.

[Mercracer]

So I removed the oil pressure sensor and put in a gauge in it's place. Then cranked it up.
The pressure gauge was bouncing quite a bit (cheap gauge). But it went to between 20-35 psi when cold and at idle. Went to 25-35 when revved. I revved the engine up quite a bit trying to hear the knock. I could not hear it with just my ears. Didn't have any body to rev for me so I could listen with hose or stick.
So I let it warm up...

Now the oil pressure is between 4-8 psi at idle. Still no knock.
I rev it and pressure goes to 10 psi. .

Only 30ish when cold and 10PSI when warm means a junk engine. Don't drive further than you can push it back as you will spin a bearing when it is least convenient. Time for an Explorer motor swap...

[sly]

84 F150 custom king cab with the 302... spun a rod bearing... knocked hard for another 10K before it was sold off and out of the loop (unable to find out about how it was doing - 7k before my dad sold it to a friend of his and the friend drove it for another 3k hauling and towing stuff before selling it yet again). Lopo rod knock is not the end of the world... just don't expect to ever hammer the throttle when it starts knocking hard.

[Neal 97 250]

This.

So what are you trying to say here???

so I changed the oil and put in 20W 50 and a motocraft filter. It didn't knock at all at any RPM, then... it got warm!
It started knocking like it did last night. But I kept going, getting it warmer. Then it started knocking at idle. It is definately a deep knock towards the front down low. I thought about adding Lucas oil treatment. It is very thick but at $11.99 that will blow the frugal budget for sure. LOL

I will take it to the gas station (~1-2 miles from home) them maybe even try the grocery store but I do not expect much here. Heck I may even try adding gear oil. (just kiddin).

Maybe try the car wash before I park it. I am definately going to pull the engine and blow the budget all to hell. It is time for a new engine. I'm thinking newer Exploder GT40p engine. But please help me with this decision.



I need help with the engine to buy.
Is the only difference between the H.O. engine and the Explorer engine just the forged pistons vs. cast pistons.
Are the cams the same? If not what is the lift and duration of the two cams?
I really just want to know the differences and the best/strongest option.

Should I look for a HO engine or Explorer? i want the best I can get because I tend to push things to the max.

[gadget73]

the "this" means I agree with what he said. Drive it as-is while you get your new motor ready. I wouldn't run it forever but I wouldn't be afraid to use the car either. I've seen people drive these things with engines that sounded like they should explode, oil idiot light on the whole time, and they just kept going and going.


cam, heads, and intake are different Explorer vs HO. The pistons are acually hypereutectic on the Explorer, not cast. Strictly speaking, the forged are stronger but unless you're going with a lot of nitrous or boost it really doesn't matter. With an NA motor, you'll never exceed the limitations of the hypers.

Explorer cam specs:
.264" intake cam lift
.280" exhaust cam lift
256º intake duration
266º exhaust duration
intake valve opens 10º BTDC
intake valves closes 66º ABDC
exhaust valve opens 66º BBDC
exhaust valve closes 20º ATDC
30º overlap

Lift is at the cam lobe. Multiply by 1.6 to get valve lift.



Its the same as the 351 trucks and 94+ 302 trucks and Explorers.

HO cam specs:
.278" intake cam lift
.278" exhaust cam lift
266º intake duration
266º exhaust duration
intake valve opens 17º BTDC
intake valves closes 69º ABDC
exhaust valve opens 67º BBDC
exhaust valve closes 19º ATDC
36º overlap

ditto the multiply by 1.6 for valve lift.
there are also better cams out there, though you might need to switch to mass air to make them work correctly. The Comp Cams XE258 should probably work very well, and while I'd like to try it, other things have kind of gotten in my way like having half of my car replaced. Also something about a missing lower intake manifold that I was planning to send out to be ported ahead of any planned cam swap.

[Neal 97 250]

OK the HO is the definate better swap.
But however for the money the Explorer may be the best for the money.

Is the HO only available in the Mustang?


I will check the price differences.
I understand the explorer '97 - '01 is the GT40p, but what should I look for if I want the HO?




P.S. Gadget thanks for the great info.

[91waggin]

Is the HO only available in the Mustang?


I will check the price differences.
I understand the explorer '97 - '01 is the GT40p, but what should I look for if I want the HO?




P.S. Gadget thanks for the great info.

HO Came in EFI 5.0 mustangs and most EFI 5.0 Lincoln MK VII's.

Dunno if you can say that the HO is decidedly the better. From what I understand, they both have their advantages and disadvantages. The basics are that the Explorer cam is for low-end grunt, to get the bastard rolling off the line, while the HO cam is designed to get the power once you wind it up, and isn't nearly as good off the line, since it was designed for a lighter sports car.

[Lincolnmania]

as others posted, keep driving until you get a new engine ready to install

the ho was available in the:
87-95 mustang (86 too but only 200 hp)
88-92 lincoln mark VII (86-87 LSC too but only 200 hp...some later 87 LSC's have the 225hp ho)
91-93 thunderbird and cougar (i have a 92 cougar ho in my 92 grand marquis)

96 and up to 12/96 build 97 explorer and mountainer 5.0 have gt40 heads

the explorer and mountaineer 5.0 up to 01 have gt40p heads

[Neal 97 250]

Lincolnmania,
Thanks for posting the vehicles I need to look for.
That helps me more than you would imagine.

Sounds like if I find a Lincoln Mark VII I will be set with the engine AND the computer.
Kool!

[Mike J.]

so I changed the oil and put in 20W 50 and a motocraft filter. It didn't knock at all at any RPM, then... it got warm!
.

I may be off base on this one but my engine made more noise when I changed to 15w40... so I changed back to 5w30 mobil one.. and it is very quiet now. I found that the thinner oil quieted it.. while the thicker stuff made it more noisy.

I would not be running the thicker oil.

my 1.5 cents... it is not worth 2 cents.

Mike J.

[gadget73]

honestly the explorer motor is the better swap. Pistons aside, everything else on the Explorer engine is way better than the HO stuff, and really the pistons aren't much worse. There is more work involved with the Explorer since you have to change the timing cover and oil pan, but thats not really major. The heads and intake on an HO motor are just not that great.


The performance difference in the cams is probably not as big as the numbers might imply. My car has an Explorer cam, and Lincolnmania's car has an HO cam, but otherwise they're extremely similar cars and engines. I've driven both quite a bit, and while there are differences in how things feel, its probably not as dramatic as the numbers may imply. Theres a 0.08 second difference in 1/4 mile times, though the runs weren't at the same time or on the same track. 20 hp difference on the dyno, but that was before I fixed some running issues and ditto on different time/place. I know if I dynoed my car again that power difference would decrease. 1/4 times may remain pretty close to the same though, but its hard to say. I could probably explain that time difference with the difference in rear gears too.