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Old 09-29-2018, 06:11 PM   #1
Robert1970C20rstbukt
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'84 454, oil in coolant????

Today I was checking the truck and it was low on oil, took about two quarts to get it in the operating range which is very odd. Normally it will use a half quart between oil changes, mostly from leaking valve covers I'm sure lol. Checked power steering, brake fluid, then found nasty brown liquid in the overflow. Pulled the radiator cap off and it had the same stuff in it, thick, light brown, and smells like oil. Pulled the radiator drain plug and it had clean coolant in bottom, let it drain about a gallon and it was still clean. I drove it to my parents house a few miles and checked the oil again, still full and clean with no coolant contamination. My Dad and I rebuilt this engine almost five years ago and it's been running great, has about 45K on it since the rebuild. Had the heads redone by a machine shop, they said they were in good condition and they did a valve job on them and resurfaced them. We checked block and it was good as well. I've ran it all these years, never had any issues. It never overheated, never used oil or coolant. My Dad's not sure what it could be either, any help would be great. I plan on doing a compression test tomorrow, and possibly renting a combustion leak tester from Oreilly's also before I tear into it.
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1984 Chevrolet C30 welding truck 454/SM465
1977 GMC C15 pickup 350/TH350
1970 Chevrolet C20 pickup 307/TH400
1970 Chevrolet K20 Suburban 454/TH350
1969 GMC 8500 fire truck 478M V6/5 spd 1200 gallon pumper

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Old 09-29-2018, 10:59 PM   #2
wildwilly4x4
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Re: '84 454, oil in coolant????

if its not coming from any kind of oil coolers in the radiator, then it has to be coming from either the head gaskets or block damage. Not easy to diagnose something like that over the net. Sounds like you have some troubleshooting to do.
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Old 09-29-2018, 11:04 PM   #3
mongocanfly
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Re: '84 454, oil in coolant????

Def not good....either head or intake gasket would be my guess...
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Old 09-29-2018, 11:13 PM   #4
Robert1970C20rstbukt
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Re: '84 454, oil in coolant????

It has a four speed, so I don't use the oil cooler in the rad. I'm hoping it's just a head gasket issue, or a bad head at the worst.
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1984 Chevrolet C30 welding truck 454/SM465
1977 GMC C15 pickup 350/TH350
1970 Chevrolet C20 pickup 307/TH400
1970 Chevrolet K20 Suburban 454/TH350
1969 GMC 8500 fire truck 478M V6/5 spd 1200 gallon pumper
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Old 09-30-2018, 06:44 AM   #5
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Re: '84 454, oil in coolant????

Can't think of anything in the intake or heads where you have pressurized oil that can force its way into the coolant. Usually gasket problems or cracked heads lead to coolant in the oil.

Was there ever trans oil in that radiator cooler? Maybe it rotted out and leftover oil mixed with coolant at the same time your normal oil losses worsened to lead to a 2 quart low condition.
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Old 09-30-2018, 03:57 PM   #6
Robert1970C20rstbukt
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Re: '84 454, oil in coolant????

The radiator has a cooler in it, but I never used it since it was new. Still has the block off plugs in it, I'm hoping it's just the head gasket/s. I started it with the cap off and I can see bubbles forming as soon as it starts, so I'm hopeful that the block is alright. I've just never seen so much of an oily looking mess in coolant before, and not having coolant in the oil pan.
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1984 Chevrolet C30 welding truck 454/SM465
1977 GMC C15 pickup 350/TH350
1970 Chevrolet C20 pickup 307/TH400
1970 Chevrolet K20 Suburban 454/TH350
1969 GMC 8500 fire truck 478M V6/5 spd 1200 gallon pumper
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Old 10-01-2018, 12:34 PM   #7
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Re: '84 454, oil in coolant????

Sorry, but I haven't ever run into having oil in the coolant either. You're the first person I've seen on here from Beeville. I grew up there. Good luck with the troubleshooting.
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Old 10-01-2018, 07:58 PM   #8
Robert1970C20rstbukt
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Re: '84 454, oil in coolant????

Yep born and raised here. The bit of oil I saw in the top of the rad was very odd, that's what really got me worrying. My Dad and I looked at it after work today, compression tested from 145 to 155 except for #2, went to 120 and started bleeding down slowly. #2 plug was wet, #4 plug was as well but not as much as #2. Really strange as I didn't notice any smoke from the engine when it was running either. Oil looks like it's leaking from the front of the passenger side head/block area also. When I get time I'm going to pull the intake and heads and get them checked out, hoping I'll find a messed up gasket under there.
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1984 Chevrolet C30 welding truck 454/SM465
1977 GMC C15 pickup 350/TH350
1970 Chevrolet C20 pickup 307/TH400
1970 Chevrolet K20 Suburban 454/TH350
1969 GMC 8500 fire truck 478M V6/5 spd 1200 gallon pumper

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Old 10-01-2018, 10:30 PM   #9
tucsonjwt
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Re: '84 454, oil in coolant????

Have you checked your spark plugs? I have had 2 454 squares and neither burned any oil, but everybody else I know who has had a BB says they burn at least a quart between oil changes. Even with leaking valve cover gaskets I have not lost any oil. I now use steel core valve cover gaskets with spreader bars and all valve cover leaks have stopped.

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Old 10-02-2018, 09:49 PM   #10
Robert1970C20rstbukt
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Re: '84 454, oil in coolant????

Yeah in my last post I talked about the spark plugs. The only leak at the valve covers were at the rear of both of them, no oil leaking up front. There was oil coming from between the head and block, and ran down onto the fuel pump. Pulled the pass. side head today, looked like it did have a leak at the #2 cylinder. Will take both heads to get checked at the machine shop for warping/cracks Thursday.
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1984 Chevrolet C30 welding truck 454/SM465
1977 GMC C15 pickup 350/TH350
1970 Chevrolet C20 pickup 307/TH400
1970 Chevrolet K20 Suburban 454/TH350
1969 GMC 8500 fire truck 478M V6/5 spd 1200 gallon pumper
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Old 10-07-2018, 09:40 AM   #11
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Re: '84 454, oil in coolant????

Quote:
Originally Posted by Dead Parrot View Post
Usually gasket problems or cracked heads lead to coolant in the oil.
I agree, add crack in block. I would pressure test cooling system!
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Old 10-09-2018, 06:49 PM   #12
Robert1970C20rstbukt
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Re: '84 454, oil in coolant????

Well everything checked out OK, just about back together will have it fired up tonight if all goes well. Work leaves me very little time do do anything lately. I'm really hoping it's not the block, we'll see what happens.
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1984 Chevrolet C30 welding truck 454/SM465
1977 GMC C15 pickup 350/TH350
1970 Chevrolet C20 pickup 307/TH400
1970 Chevrolet K20 Suburban 454/TH350
1969 GMC 8500 fire truck 478M V6/5 spd 1200 gallon pumper
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Old 10-10-2018, 01:15 PM   #13
andyh1956
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Re: '84 454, oil in coolant????

Just thinkin out loud here...The puppy here at work was working on his wife's ride, had coolant leaks. When he got ready to pour the coolant back in the reservoir he poured it instead into the open oil filler on the engine!
The same coulda happened to your truck, only in reverse.
Stuff happens!
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Old 10-10-2018, 05:46 PM   #14
cadillac_al
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Re: '84 454, oil in coolant????

I put pond water in a radiator once when I overheated on the road and it all turned to black muck in the radiator 2 months later. The pond water looked clear when I put it in. So the 454 didn't have a bad headgasket?
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Old 10-11-2018, 10:29 PM   #15
Robert1970C20rstbukt
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Re: '84 454, oil in coolant????

I was sure it had a leaking head gasket, but the guy from the machine shop that checked the heads looked at gaskets and said they weren't leaking. Stupid me should have done a leak down test on the cooling system then it would have showed the problem right off, live and learn I guess. It does seem like the block is cracked, oil galley leaking into the water jacket is what he thinks. Oil started mixing into the coolant again as soon as it fired up, now I'm on the hunt for another block or whole engine. Shame I don't have a couple grand laying around, I'd just buy a new crate engine from Jegs or Summit lol.
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1984 Chevrolet C30 welding truck 454/SM465
1977 GMC C15 pickup 350/TH350
1970 Chevrolet C20 pickup 307/TH400
1970 Chevrolet K20 Suburban 454/TH350
1969 GMC 8500 fire truck 478M V6/5 spd 1200 gallon pumper
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Old 10-21-2018, 07:00 PM   #16
AussieinNC
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Re: '84 454, oil in coolant????

The block will have multiple tiny cracks in the lifter valley along the cam lube bores...these will extend into the cooling system spaces and as Oil pressure is above water pressure the oil will escape and pollute the cooling system.

Only choice is another engine sadly...

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Old 10-22-2018, 09:53 AM   #17
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Re: '84 454, oil in coolant????

Nothing to lose, use block sealant. Had one cracked under lifter valley that would leak occasionally. Drive it till you find a replacement
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Old 10-22-2018, 11:09 AM   #18
andyh1956
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Re: '84 454, oil in coolant????

Quote:
Originally Posted by JMac11 View Post
Nothing to lose, use block sealant. Had one cracked under lifter valley that would leak occasionally. Drive it till you find a replacement
What he said, nothing to lose. Purple power will clean good & I've had best luck with K&W
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Old 11-27-2018, 08:38 PM   #19
Robert1970C20rstbukt
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Re: '84 454, oil in coolant????

Update time, been busy with family and work. I actually couldn't run the engine in the truck anymore as it was starting to mix water in the oil, it's been parked since the beginning of October. I don't want to take a chance on block sealer, don't think it would work anyway since the oil pressure is 60 psi vs coolant at 15 tops. I asked around locally and scored a complete 454 from a '78 Winnebago with about 48K miles for $500. I checked it out and fired it up while it was in the motor home and it ran like a top, no odd noises or smoke. I had a friend bring their winch truck over and we used a stinger pole I built to reach in there and hook up the engine. Once I got it home I took the pan off and everything looked real clean inside. I replaced the oil pump, timing set and all gaskets and seals. I transferred the intake from the original engine because the carb on my truck used the hot air choke and not the spring type. Once I got it buttoned up I gave it a coat of black paint. Dad and I got it dropped in Sunday, fired it up yesterday and it sounds even better with the dual glass packs.
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1984 Chevrolet C30 welding truck 454/SM465
1977 GMC C15 pickup 350/TH350
1970 Chevrolet C20 pickup 307/TH400
1970 Chevrolet K20 Suburban 454/TH350
1969 GMC 8500 fire truck 478M V6/5 spd 1200 gallon pumper
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