3.7 water in oil whats wrong ?

[mlb31384]

recently bought a boat with the 3.7 lx motor 180hp. i dont know what the problem is.
1. water in oil
2. did cylinder compression test 125, 125, 120, and 130
3. hooked up a leak down tester for cooling system held 20psi w sparkplugs out
4. no power when in water
5 had compression tester hooked up to cooling sytsem while running in water and it maxed out the meter at 30psi and actually spewed antifreeze out of the cap
when this happened motor was ran under a load strapped to my trailer at the boat launch holding steady at 2200-3500 rpm in forward gear

 

[HT32BSX115]

Re: 3.7 water in oil whats wrong ?

Howdy,

Well,

recently bought a boat with the 3.7 lx motor 180hp.

I hate to be the first one to tell you but your first problem is the above.....

Do a little reading, http://www.sterndrives.com/470information/470coolantleakrepair.html

Also, do a search on iBoats for Mercruiser 470 3.7L problems and you'll have a lot of reading to do.

Now I suppose it's not the end of the world. You can fix most of the "problems" up to and including replacing the engine etc.

It just won't be as easy and as inexpensive as engines that are still being produced by Mercruiser.

Sorry about that.


First thing you'll need to do is some research on your engine. Second, get an OEM service manual. (Seloc/Clymer will not cut it)

Find a forum that has people with the same engine series. (There's a LOT of people here with them)



Good luck.


Rick

 

[mlb31384]

Re: 3.7 water in oil whats wrong ?

i know the engine isnt the greatest design. believe me i hsve been reading online for 2 days straight almost and have not found a similar scenario

 

[HT32BSX115]

Re: 3.7 water in oil whats wrong ?

had compression tester hooked up to cooling sytsem while running in water and it maxed out the meter at 30psi and actually spewed antifreeze out of the cap

Can you explain the above a little?

Are you saying that when the engine was running it produced 30 PSI in the cooling system?

I don't think you want to put more than the RATED cap pressure on any cooling system. I'm surprised you didn't blow a hose or the heat exchanger.....


If the engine is producing that kind of cooling system pressure it sure sounds like a head gasket leak (evidently a common problem on the 470)

 

[mlb31384]

Re: 3.7 water in oil whats wrong ?

the engine created the pressure. i thought it was a head gasket but why does it have perfect compression. and why did it pass the coolant leak down test? this is confusing

 

[HT32BSX115]

Re: 3.7 water in oil whats wrong ?

the engine created the pressure.

Immediately? or did have to get completely up to operating temp?

It couldn't do this with the cap on because the cap would start venting at it's rated pressure. (whatever that is.... 13/16 psi etc)

 

[mlb31384]

Re: 3.7 water in oil whats wrong ?

it took about 5-10 minutes of 2200-3500 rpm in forward gear

 

[HT32BSX115]

Re: 3.7 water in oil whats wrong ?

I would still bet that it's a head gasket leak that occurs when the engine gets hot.

You would think that a leak down would catch it....

 

[sdoomaha]

Re: 3.7 water in oil whats wrong ?

How much "water" are you getting in the oil? What is your temperature running? Are you losing a corresponding volume of antifreeze from your closed cooling system as you are gaining in your oil pan?

Cam shaft seal? If you've read about the 470 you're probably familiar with this very common issue and the speedy sleeve fix.

What is your exhaust looking like? Clean or billowy (if that is such a word) white smoke? Smell the exhaust...have any anti freeze smell to it especially at start up? If so, I would be confident in a head gasket problem.

I got tired of guessing as well and just tore mine apart (again). Pulling the head for me and a buddy (just weekend warriors) in my driveway is an hour and a half job. Motors got it's faults but being easily accessible and easy to tear down is not one of them.

Mine was heating up...and drinking anti freeze. After testing heat exchanger and exhaust manifold, the head gasket finally really gave up and started getting coolant in the oil. Head gasket between the water jacket and #1 cylinder was leaking. Compression was still good in comparison to the other cylinders...apparently because of the coolant leaking into the cylinder was compensating for the leaking head gasket. How many times did you take the compression on each of the cylinders? Did the reading vary for a particular cylinder or cylinders when taking more than once?

Good Luck...hope you get it figured out.

 

[mlb31384]

Re: 3.7 water in oil whats wrong ?

im goin to replace the head gasket n see if that helps if not maybe i need to sleeve the cam what do you think am i doing the right thing

 

[solar7647]

Re: 3.7 water in oil whats wrong ?

Yea your doing the right thing. The head gasket is a great place to check in this engine. I run the same engine, but dont have many issues with it. I have found that as long as you take proper care of them with out modifying them they run great. If the last owner didnt do the up keep then you may have issues. If they over heat they get some gramlins that are hard to chase down. Do you know what size heat exchanger is on it? If it has a 3 inch try to find a 4 inch and put that on there. They where standard on later models of the engine. I only say because the 3 inch are more prone to over heat. Also make sure your are using the proper coolent, dont every use water as a substitut.

I say change the gasket put some clean oil in it and see what you get. If all is good just keep up on maitance. They get a little cranky when it comes to oil changes so make sure your doing one every season if you dont use it alt if you use it a lot do one every 100 hours.

Good luck

 

[bhammer]

Re: 3.7 water in oil whats wrong ?

I would look at the head gasket as well and make sure the head isn't warped. Unless you have the leak out of the weep hole on the timing cover, you don't need to do the speedie fix. this won't casue the issue you are describing.

 

[stonyloam]

Re: 3.7 water in oil whats wrong ?

the engine created the pressure. i thought it was a head gasket but why does it have perfect compression. and why did it pass the coolant leak down test? this is confusing

You should have in the 150 range, so you are a little low. My opinion, you have a bad head gasket. Pull the head and replace the gasket with a genuine Mercruiser oem gasket (not aftermarket). While you are at it, it could probably use a valve job. Coolant leaking into the cylinders can corrode the valve seats. It probably passed the test because 20 psi was not enough pressure to push a significant amount of coolant into the cylinder, and the meter maxed out while running because of compressed gasses (120 psi) passing from the cylinder into the coolant. Coolant can also leak into the oil from a bad head gasket. With a valve job and head gasket it should run fine (I hope). Good luck!