Mercruiser 470 oil in coolant?

[copierkat]

Hi all. I started my recently purchased 83 Celebrity with 470 Mercruiser for the first time tonight. I only ran it a few seconds with muffs a couple times and shut it off. I went into town to rent a compression tester because one of the plugs came out clean when changing them, like there was a coolant leak into that cylinder. Before starting with comp test, I added anti-freeze to the tank on top since it was empty. After filling it, it looked dirty brown, and when I stuck my finger in it, it was oily. Also, there is no oil on the dipstick, although it was clean and on the full mark last fall. I do not want to start the comp test with oil in the coolant. Should I drain it and re-fill? What kind of oil should I put in this engine? Can I use 5W30? Dave

 

[Levithan]

Re: Mercruiser 470 oil in coolant?

Oil in the coolant=bad.
Head gasket or crack somewhere internally in the engine.

 

[copierkat]

Re: Mercruiser 470 oil in coolant?

Do I need to do a comp test? Or start ripping it apart?

 

[Levithan]

Re: Mercruiser 470 oil in coolant?

Compression test may tell you if you have a head gasket issue and various other problems, however it will not show if the crack is elsewhere in the block.
Pull the plugs and see if you have coolant or oil in any of your cyl's.

 

[achris]

Re: Mercruiser 470 oil in coolant?

Due to the design of the 470, it could be something as simple as the camshaft seals leaking. That's what I'd be checking first.

Chris......

 

[copierkat]

Re: Mercruiser 470 oil in coolant?

Compression test may tell you if you have a head gasket issue and various other problems, however it will not show if the crack is elsewhere in the block.
Pull the plugs and see if you have coolant or oil in any of your cyl's.

Thanks Levithan. I did replace all plugs. On inspection, I did not see oil in cylinders, but on the cylinder closest to bow, the old plug was clean, washed like antifreeze has been in that cylinder. Looking in oil fill hole, it looked like a puddle of green antifreeze was in there.

 

[Levithan]

Re: Mercruiser 470 oil in coolant?

Sounds like a head gasket if there is coolant in the cyl, do the compression test, should tell you.
Don't run the engine anymore until you find out what the problem is.
If it is a gasket issue, it can be fixed, however if too much coolant goes through the bearings it will wipe the babbet off of them and the engine will need rebuilding.

 

[copierkat]

Re: Mercruiser 470 oil in coolant?

Due to the design of the 470, it could be something as simple as the camshaft seals leaking. That's what I'd be checking first.

Chris......

Thanks Chris. With the camshaft seal leaking, could the oil leak out over the winter? Possibly why it was full last fall and not now? I have the comp tester rented for 2 days. Is it worth doing a comp test on each cylinder? Do I have to pull engine to check camshaft seals?

 

[copierkat]

Re: Mercruiser 470 oil in coolant?

Sounds like a head gasket if there is coolant in the cyl, do the compression test, should tell you.
Don't run the engine anymore until you find out what the problem is.
If it is a gasket issue, it can be fixed, however if too much coolant goes through the bearings it will wipe the babbet off of them and the engine will need rebuilding.

OK, thanks Levithan. I will do the comp test tomorrow and post results.

 

[achris]

Re: Mercruiser 470 oil in coolant?

Oil won't leak out without the engine running. If you have space at the front of the engine to work, you can replace the seals (and speedi-sleeve the camshaft) without removing the engine. If you have the compression tester, do the compression test. I would think a leak-down test would be more effective though.

 

[stonyloam]

Re: Mercruiser 470 oil in coolant?

Do the compression test, and a cooling system pressure test (borrow the tools from Autozone) likely a head gasket. Replace with an OEM Mercruiser gasket (designed specifically for the 470). I run 25W40. The old recommendation was straight 40 wt. 5W30 would be too thin IMHO.

 

[copierkat]

Re: Mercruiser 470 oil in coolant?

Do the compression test, and a cooling system pressure test (borrow the tools from Autozone) likely a head gasket. Replace with an OEM Mercruiser gasket (designed specifically for the 470). I run 25W40. The old recommendation was straight 40 wt. 5W30 would be too thin IMHO.

OK, the compression test from bow to stern was 105, 110, 105, and 120. Are these OK? Will do cooling system pressure test next. Dave

 

[Don S]

Re: Mercruiser 470 oil in coolant?

Looks like your engines getting tired with those compression numbers, you should be up in the 150 range. But that isn't your problem.

A compression test isn't likely to find a small leak putting oil into the coolant. A leakdown test of each cylinder would be a better test. Just leave the heat exchanger cap off and watch for bubble while doing the leakdown test.

When you do the cooling system pressure test, make sure you drain all the coolant first. You will most likely have to hear the leak, as it's not going to external for you to see it.

 

[copierkat]

Re: Mercruiser 470 oil in coolant?

Looks like your engines getting tired with those compression numbers, you should be up in the 150 range. But that isn't your problem.

A compression test isn't likely to find a small leak putting oil into the coolant. A leakdown test of each cylinder would be a better test. Just leave the heat exchanger cap off and watch for bubble while doing the leakdown test.

When you do the cooling system pressure test, make sure you drain all the coolant first. You will most likely have to hear the leak, as it's not going to external for you to see it.

I went to O'reilly Auto Parts to rent the leakdown tester, but all they had was one where you put fluid in it and it changes color if there is a problem? I did get the radiator pressure tester and will let you know how that goes. Will have to look elsewhere for leakdown tester. Dave

 

[achris]

Re: Mercruiser 470 oil in coolant?

I went to O'reilly Auto Parts to rent the leakdown tester, but all they had was one where you put fluid in it and it changes color if there is a problem? ...

That's an alkalinity test, not a leakdown test..

 

[copierkat]

Re: Mercruiser 470 oil in coolant?

I did the cooling system pressure test. Pumped it up to 18PSI and it dropped to 15PSI after about 15 minutes. I could not hear any leakage. The only problem I saw was antifreeze dripping from inlet hose to engine. How do you drain all antifreeze? I sucked it from the top, but there still was antifreeze in hoses. Do I just take off hose clamp and drain it that way? Maybe with it empty I would be able to hear leakage? Will try to find leakdown tester at another auto parts store and do that test next. Pic of engine shows side hose is attached to. Serial number of engine pictured also. Thanks, Dave

 

[Don S]

Re: Mercruiser 470 oil in coolant?

Here is the draining procedure. After thinking about it, not sure a leak down test will tell you if oil is leaking into the coolant or not, are any of the spark plugs covered in oil? If no oil there, the combustion chamber isn't pumping oil to your cooling system.
That tester kit from O'rilley is probably a test to check for combustion gas in the coolant. Would work in place of the leak down test for finding cracked heads, block, and blown head gaskets.

Here is how to drain the cooling system.

 

[copierkat]

Re: Mercruiser 470 oil in coolant?

I am going to replace the head gasket and related gaskets. Is there a kit? Part number? Thanks for everyones help! Dave

 

[stonyloam]

Re: Mercruiser 470 oil in coolant?

Use the OEM Mercruiser head gasket.

 

[achris]

Re: Mercruiser 470 oil in coolant?

Part number?

Use the OEM Mercruiser head gasket.

27-13709, that's just the head gasket, you'll need the rocker cover gasket too (27-73666)....