Technical Oily slick in water/coolant 454

When I worked for the govt. ATF had a early 90's 1 ton with a 454. They took it to the Chevy dealer for some exhaust manifold leaks.
In the process of replacing the exhaust gaskets and a cracked exhaust manifold they broke off a couple of bolts and had to remove the heads and take them to a machine shop to remove the broken bolts.
They reinstalled the heads and one of the ATF agents was going to South Carolina from Brunswick,Ga. He got to the border and the motor blew up. They towed it back to the Chevy dealer. I got a call to go inspect the engine and authorize the repair. The dealership vey carefully cleaned everything up so there was no fault of theirs. I looked up at the bottom of the block with the pan off and there was one drop of bright green antifreeze on the crankshaft. I asked when Chevy started to water cool the camshaft. The
shop foreman knew he had been had,and asked whose ass he had to kiss to make it right.
I told him he didn't have to kiss anybody's ass,but he did have to put a new motor in the truck.
he balked and I had the Govt attorney give him a call and the dealership put a brand new crate motor in the truck.
that's what you might find if you pull the pan. Coolant and bearings do not play well together.

 

Not hateful numbers. 2 or 4 bolt? 1st and foremost, 4 bolt mains don't make HP but they are stable up to some fairly big TQ. The cheater way to even decide to look is if there's oil cooler plugs in the block near or above the filter. All 4 bolts have em that I've seen (seen a bunch of em) and very few 2 bolts got em. If it is 4 bolt you might be right on the edge of the 'Mercury Marine' 4 bolt blocks that were used in production for all GM products. Late 80s-early 90s, MM took over block production for a while, I think because the general was tooling up for the MK V. That's some of the overspray you get during national event level bench racing Why mention it? 2 reasons. They're a high nickel iron. That's a good thing. 2, cylinders 6 and 8 got the worst of the normal core shift and overbores bigger than +.060 can net a crack in one of em.I was .100 over and eventually cracked #6. None of this means much in your case unless you plan to go racing but maybe it's just food for thought. BTW, used to be able to tell a Mecury Marine block by 2 small pilot holes just above the filter boss where the blocks for marine use were tagged. I had em, my block was an 89 crate motor core.

 

99% sure it's a 2 bolt main engine

but you wont know if you don't look...and it doesn't matter unless you're going to do a lot of other mods to the engine, so that it could possibly get some benefit from 4 bolt mains.

 

Ill be happy with a 2 bolt, I don't have any plans to try and make huge numbers. I just like knowing what Im working with, and I always try and clean out the pan on stuff with unknown or questionable history before an oil change. I havent been able to get under it yet to see what kind of clearance there is. I know it has some strange iron manifolds that are super close to the frame rails. Its pouring rain today hope to post some progress in the next couple of days.

 

Nothing wrong with a 2 bolt main block. My old 38 Chevy sedan with the 454 was a 2 bolt, cast crank, World Products Merlin oval ports, 0.060 over, and in previous life in my OT drag Camaro used to buzz 6000 all the time. It was low budget built on a used street flat top short block. Put new rod and main bearings, a very big hydraulic flat taper cam, the good heads, and ran a 1050 dominator at the track. Street use in the 38 ran a 750 mech sec, with more closed exhaust. Still ran it to 6000. That engine ran great and best of my knowledge still doing well. At least never heard from buyer about any issues.

So that's a long story that you can have confidence in your basic truck engine for now. Put decent heads and more cam, easy fun street engine.

Sent from dumb operator on a smart phone

 

I ran 2-bolt main big blocks in the stock cars. Kept the revs down below 6500 but they still made plenty of power off the corners.

 

Chevy put 4 bolt mains and steel cranks in all the medium duty truck engines (366-427 tall deck), but used 2 bolt blocks and cast cranks in almost all the light duty (1/2 to 1 ton) truck engines. There must be a reason for this.

 

Regarding the oil sheen in the coolant; what condition are the hoses in? Rubber contains oil, breaking down rubber hoses displaces oil into the coolant. That would be my guess of what's going on, without actually seeing it for myself. When you did the compression test, it does't sound like you repeated it "wet" afterwards; you know, toss a little oil into the cylinders and repeat the test to see if the readings improve, indicating worn rings/cylinders? At least all your readings are fairly close to one another. Years ago, I had some concerns an engine I had, had a cracked block or head. I tossed a little Muriatic acid into the coolant water, ran the engine for a while, drained and flushed it, then neutralized the acid with baking soda, and flushed it again. Then, I put a quart of egg keep, AKA, water glass, AKA,sodium silicate, and water into the cooling system, and ran the engine again. It was during that last running of the engine, that a radiator hose blew off the water pump! So, I wound up with sodium silicate all over the under-hood area, and it quickly dried due to the heat; what a mess!. You'll never get that dried stuff off of everything, and pretty much have to just paint over it. After all that, it just needed a new radiator cap, that's where the coolant was going, I just did't notice/see it. Anyway, the drying sodium silicate fills in the defects/cracks, and seals things up. It's even used in some radiator stop leak products. I am Butch/56sedandelivery.

 

Just wanted to give an update and resolution to my oil in the coolant issue. Ill likely start a project thread for this truck. I really appreciate the help given.

I must have flushed this truck 12 times so far.

1. I discovered the rust water and hose flushed until clear.
2. Refilled with water and used Prestone flush. This is when I noticed the oil slick.
3. Refilled with water, flushed, still oil present. Not a lot, just a sheen.
4. Repeat water flush. Run for 15 minutes.
5. Repeat. Run for 15 minutes.
6. Water crystal clear at this point, besides a slight oil sheen still.
7. I used ALL brand free and clear clothes detergent, ran for 15. Flush came out very light brown and stinky.
8. Mixed 2 lbs of citric acid powder with around 3 gallons of water, ran for about 20 minutes. Drained out green, orange, and brown. This step was huge. My only explanation was that there was some cavity in the block sealed off with corrosion and the citric acid cleared it out releasing trapped coolant.
9. Dumped half box of baking soda in, refilled with water to neutralize acid. Ran up to temp and let it sit for a few hours. Drained out light brown. NO OIL SLICK finally!
10. Water flush clear. Ran 15.
11. Water flush clear. Ran 15.
12. Filled with coolant mix, changed all hoses. Installed new thermostat.

On top of this I used motor flush and changed oil. The pan is pretty ugly so I left it on for now until I find a nice replacement. I took the wife for a neighborhood spin and the oil had not returned. I borescoped the water pump and it went from neon orange to clean silver. What a relief!