Sludgy 1990 F150 5.0

[cbrf3]

Sounds cool but we do not have the money nor the experience to perform a motor rebuild. We have no history on the truck unfortunately.
I still feel like a slow clean up can save this guy and turn things around just like when I had to scrape the junk form my slant six in 1980 from using good olde QS Deluxe.

 

[OVERKILL]

Rebuild time! A set of GT40 heads will do the trick.

Speed density with the LoPo firing order and a broomstick cam, I don't think GT40's are going to do much to wake it up. IIRC, it's batch fire and still flat tappet, so you could swap in an HO cam (block should already be setup for roller lifters) which would make more sense with the head swap but at that point it's cheaper to just swap in an HO longblock, which is exactly what I did the last time I went down this road.

 

[OVERKILL]

Sounds cool but we do not have the money nor the experience to perform a motor rebuild. We have no history on the truck unfortunately.
I still feel like a slow clean up can save this guy and turn things around just like when I had to scrape the junk form my slant six in 1980 from using good olde QS Deluxe.

This is one of the Mobil 1 0w-40 slides:

 

[BLND1]

Speed density with the LoPo firing order and a broomstick cam, I don't think GT40's are going to do much to wake it up. IIRC, it's batch fire and still flat tappet, so you could swap in an HO cam (block should already be setup for roller lifters) which would make more sense with the head swap but at that point it's cheaper to just swap in an HO longblock, which is exactly what I did the last time I went down this road.

my 5.0 experience is limited to fox bodies... my point was more “a complete year down is the only thing that’s gonna fix THAT.”

 

[OVERKILL]

my 5.0 experience is limited to fox bodies... my point was more “a complete year down is the only thing that’s gonna fix THAT.”

Most of mine is too, but I did do a few HO swaps into F-series trucks

Cheapest route would be a stock HO longblock, WAY cheaper than a rebuild, I've managed to score three of them in the past, all were in great condition.

 

[cbrf3]

I have seen a few pictures of the top end of sludged up motors but I have never seen anything on the pan side. I know often the pan is hard to remove as the motor needs lifting but what does the gunk stick to on the bottom side?

Is the worst evidence on the heads since the oil will just sit on top and cook a bit at shutdown?

 

[THORROMIG]

Super Tech Filters changed every 500/750/1000 miles as mentioned earlier -- cut open to verify sludge/debris/etc.. is getting to the point where you feel confident moving forward. If your content on starting with your Mobil 1 High Mileage than so be it -- I would elect for SuperTech High Mileage Synthetic for multiple oil changes first -- but just my 2 cents because of the price of the Super Tech Synthetic to start with. Good luck and please keep us posted!!!!

 

[THORROMIG]

That or Rotella T5 10W30 Semi Synthetic a couple batches.

 

[PontiacHO]

Remember, all the sludge and sediment that you are attempting to break loose and catch in the filter has to be pumped into that filter. I’ve Seen many times over an oil pump screen clogged and then you have a locked up engine. If drain back holes in the heads are open, button it up and go on about your business.

 

[berniedd]

Since it seems to run well, I suggest stay off the flushes. I'd just run cheap HDEO in it, change oil filter every 500 miles, and change oil when it gets very dark. Cut open the old filters, see how much crud it caught. Adjust filter change interval accordingly.

 

[thastinger]

IMHO that is to much to do an idle flush with diesel fuel unless you planned to drop the oil pan and clean the oil pump pickup screen.
If you hadn't have pulled the valve cover, you would have never known.
I think your safe play here would be decent oil and filters from now on and call it good. Those 302s will go a very long time.

 

[Bailes1992]

If it's running fine, why even touch it? I'd do short intervals using synthetics and I'd hazard a guess it might sort itself out.

 

[mpack88]

I ran a euro 5w40 in my 88 302 and it did something to my filter. So yes a slow clean would be better. The filter would go into bypass and make the guage bounce around. After changing just the filter it was find.

 

[RDY4WAR]

Dealing with sludge, you'll want an engine oil with a good bit of solvents like ester or naphthalene. Mobil 1 0w-40 contains a good bit of naphthalene. Red Line HP series contains up to 40% ester in their formulas. High Performance Lubricants, a site sponsor, also has a 100% ester cleaning oil that you blend at a 20-40% ratio with another oil in the engine for a few 1k mile intervals. Valvoline Premium Blue Restore is ~60% ester as well. There's a few good options to choose from. As has been mentioned though, change the filter often with any of these oils as it will get clogged up if the solvents are working as they should.

 

[cbrf3]

So my son decided to remove the rocker arms and push rods to be sure they were not blocked. All seem to be pretty clear but they got a good scrubbing then retorqued to about 20 flbs. Also a bit ago we removed the ignition parts and wonder if they are original. Wires were very hard to remove and were dated 1990. Truck is said to have 121k on it and was running quite well before digging in to replace the valve cover gaskets... Tank and fuel pump/filter have also been replaced with new. Appreciate all the comments thus far.

 

[RDY4WAR]

He didn't need to remove the rockers and pushrods to check for oil flow. Just put a socket on a drill down the distributor hole to turn the oil pump drive with the valve covers off and see if oil flows to the rockers.

Since the old rockers are off, now would be a good time to replace those old stamped steel rockers with a good set of 1.7 ratio roller rockers. An MSD cap and rotor with a set of Taylor or MSD plug wires helps those old ignition systems quite a bit.

Something I'd do, given how much it has sat and knowing what the heads look like, is probably drop the oil pan and replace the oil pump and pickup. They're cheap and not that difficult to do. If the heads look like that, the lifter valley and oil pan probably do too.

 

[cbrf3]

He didn't need to remove the rockers and pushrods to check for oil flow. Just put a socket on a drill down the distributor hole to turn the oil pump drive with the valve covers off and see if oil flows to the rockers.

Since the old rockers are off, now would be a good time to replace those old stamped steel rockers with a good set of 1.7 ratio roller rockers. An MSD cap and rotor with a set of Taylor or MSD plug wires helps those old ignition systems quite a bit.

Something I'd do, given how much it has sat and knowing what the heads look like, is probably drop the oil pan and replace the oil pump and pickup. They're cheap and not that difficult to do. If the heads look like that, the lifter valley and oil pan probably do too.

Yes, I have seen the pictures of the nasty valleys but not sure we can get the intake off without messing something up. I think the motor should be at TDC but need to figure that out and mark the distributor somewhere to keep the timing. Other issue I suppose is the fuel rail connections need to be removed (special tool?) at the back but not sure how the get the fuel injectors out, seem tight in the head.

These dang new fangled motors.

 

[SatinSilver]

The pics in the OP seem like it’s pretty rust free which is a huge plus. Looks like a keeper. Any pics of the exterior?

 

[cbrf3]

The pics in the OP seem like it’s pretty rust free which is a huge plus. Looks like a keeper. Any pics of the exterior?

It has some surface rust in the bed and on the frame rails. It also has the customary rip in the drive seat!
But overall it is solid, all lights work and has the original paint.

 

[JeffKeryk]

You are doing a great job! Hopefully that truck will be in service for many years to come.