oil cooler failure

guglielmo6160 · Post by **guglielmo6160** » Mon Jan 07, 2013 7:21 pm

ok, was out on a cruise the other day , and as always when I come back I go over all the fluids and do an inspection of the engines , belts etc. I noticed the oil level on my port engine was approx a half a quart high. My engines are fresh water cooled .Im of the opinion that my oil cooler is failing or failed. there is no indication of any oil in the engine heat exchanger and the level is perfect, In my professional opinion, there are no other issues with this engine. I will be taking the oil cooler off and checking for oil residue inside the chamber where the raw water runs,and I dont think its necc to have it sent out for pressure checking as the replacement costs, do not warrant this, and I dont want to spend money on what I think is a less than perfect test. I guess a new one will be on the way, but before I do that,,,,,,,
My question is , what is the failure rate of these stock U shaped coolers,
I have Crusaders(454) and if there is a better cooler out there, now would be the time for me to upgrade
opinions? advise?

Big D · Post by **Big D** » Mon Jan 07, 2013 7:39 pm

Pull the oil or raw water lines off the cooler and do a pressure test. If it's leaking, it would have to be ingesting water while static. While the engine is running, the raw water side would have to overcome the oil system's typical minimum 40 psi pressure. It would likely leak the other way. You may have a different issue. Has the coolant level gone down? How old are your exhaust manifolds? Are they raw water or fresh water cooled?

guglielmo6160 · Post by **guglielmo6160** » Mon Jan 07, 2013 8:11 pm

As I stated in my posting,
my engines are fresh water cooled, meaning I have a heat exchanger and raw water does not get to the engine blocks.
are you saying that 40 psi is running through the cooler assy? and water cannot get into the engine oil system? I respectfully disagree with that. if it were the other way aroud you would never know if you had a leak as oil would flow out of the exhaust system. and you would run out of oil in a hurry. I think it is possible to mix the raw water in the exchanger with oil, especially at idle speeds where the oil psi would not be lets say at normal operating pressure
my coolant level is spot on, with no evidence anywhere of oil intrusion into the cooling system

Big D · Post by **Big D** » Mon Jan 07, 2013 8:41 pm

Not saying that a leaking cooler is not a possibility hence the recommendation to test. I'm simply stating another possibility based on what I have run into over the years. And at idle you are still at 40 psi, your raw water pump will not overcome this even at higher rpm as oil pressure will rise. But as stated also, water may be getting in while the engine is static/not running. What I was asking re cooling is if your exhaust manifolds are fresh water cooled as well...big difference. If raw water cooled and older than 5-7 years in salt water applications, it is a huge consideration that the water may be coming from there. Does the engine ever sound like it's labouring when you try to start it for the first time in a given day after sitting overnight for example?

prowlersfish · Post by **prowlersfish** » Mon Jan 07, 2013 8:44 pm

Big D is correct . and most the time when a oil cooler fails you lose oil right out the exhaust . Any sighs of water in the oil ? ( milky oil ) . Is the oil thinned out ? You could be getting gas in the oil .

If your sure you getting water in the oil ( and not coolant) check the manifolds and risers .

prowlersfish · Post by **prowlersfish** » Mon Jan 07, 2013 8:46 pm

looks like Big D was posting at the same time

Big D · Post by **Big D** » Mon Jan 07, 2013 8:48 pm

prowlersfish wrote:...You could be getting gas in the oil...

Good point Paul, forgot about that one. Naturally assumed OP confirmed water.

gettaway · Post by **gettaway** » Mon Jan 07, 2013 9:18 pm

do you have remote oil filters? is this engines filter higher than the oil line inlet / oultet on the engine, could oil from the filter have drained back into the crankcase? same with the cooler?

I know on Velvet drives and my twin discs, you have to check the oil level immediatley after shut down to get an accurate fluid level reading, if they sit, it will read high as the oil will drain back to the trans.....

worth a check if there is no signs of water in your oil, and that is quite obvious----- and that makes your heart stop......

mikeandanne · Post by **mikeandanne** » Mon Jan 07, 2013 9:35 pm

As getaway said, and most oil filters I believe have check valves to stop drain back to the pan to stop dry starts.One other thing to remember is the oil will expand more than you think when it is hot.If you have one of those infrared heat guns -- shoot the pan on each engine and compare--good tools to have for this---just some more ideas to add to the others ,hope this helps---Mike

gettaway · Post by **gettaway** » Mon Jan 07, 2013 10:22 pm

Mikeanddanne...

new member ? if so welcome! thanks for the check valve comment I forgot to add that point.

guglielmo6160 · Post by **guglielmo6160** » Mon Jan 07, 2013 11:25 pm

Big D, yes I understand, good point with the static drain from the cooler.
no , no laboring on engine starts. and I am considering your advice about it getting in while static, Im leaning towards this. I m not sure about the manifolds I will check in the am, as to how they are cooled, but Im assuming the exchanger water is pumped into them (Do they have fresh water cooled manifolds and risers???) and dont see how it would get introduced into the engine oil. The oil I removed from the engine was slightly milky , so water is making its way into the oil system for sure, again, not very much, as I was running at high rpm (3400) for a while , and I would say I gainned approx a half a qt of oil.
how would water get from the manifolds into the engine, static or otherwise.? The only way would be at shut down and that would cause a hydro lock at the exhaust valves and that would be ugly, and noticeable.I know if the intake manifold gasket failed I would be getting coolant into the oil and vice versa. This is not the case. There is no adverse engine performance at all.or smoking from coolant or water on startup.The fuel dilution made me raise an eyebrow but I dont think thats the case, it would have to be running pretty rich for that to happen, and I would notice that as well.
As far as drain back, this is not the case. as I see definite signs of water in the oil. Im just happy I caught this now rather than later Everything at this point is pointig towards a failed oil cooler, and as Big D pointed out it may be static drainning into the oil system while at rest,
I will be pulling the cooler and doing a crude pressure test on it in the morning
will update
thanks to all for all the good info

Big D · Post by **Big D** » Mon Jan 07, 2013 11:52 pm

If one or both of your manifolds are bad, rusted out internally, the raw water side will leak into the exhaust side and enter a cylinder through an open exhaust valve then past the rings into the oil pan. Pretty common in salt water cooled manifolds. As stated earlier, if they are raw water cooled and older than 5 years, the possibility is close to the top of the list. Check the easy things first though like the cooler. Pressure testing it first is a lot easier than checking the manifolds in place.

Commissionpoint · Post by **Commissionpoint** » Tue Jan 08, 2013 12:14 am

G. You can always get the oil tested to see whats up with it. It might save you some time trying to track down the problem if you have access to those facilities nearby. I should think that you do in your area. Milky could be milky for a lot of reasons. You just got this boat right? Closed cooling?

Another thing. Whats the oil smell like? Like oil or used oil, or something else? Gasoline, candy, maple syrup? (I'm being serious about maple syrup)

guglielmo6160 · Post by **guglielmo6160** » Tue Jan 08, 2013 8:15 am

thanks will update by days end
Commission .. that wont be necc, I have been an import car mechanic my entire life, most of my experience is on high end cars. I run a small personal repair business here in cape coral, so I wont have to send my oil out , I know it has water in it. I would bet my life on it. lol My manifolds are approx 9 months old according to the receipts the PO left me. But I will check anyway,
when I start my engines, there is absolutely no indication of water in the cylinders at all, no smoke, no hydro lock , nothing .
will get to the bottom today,,
Im putting my money on the cooler,,,

Commissionpoint · Post by **Commissionpoint** » Tue Jan 08, 2013 11:37 am

Cool G. I am up to 4 Mercedes now. W210, W123 Euro, and a gen1 and gen2 W126. I like certain imports too.

Good luck figuring that out. Exchangers sound like a decent possibility. Lets us know what you discover.