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Mercruiser 470 Probs

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texel_tom

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"I have just bought a 1981 Spo

"I have just bought a 1981 Sportcraft with a Mercruiser 470 which I can see from the forums gets mixed reviews. This is a winter project boat which didn't cost a lot and I am at the stage of deciding whether to stick with the 470 or upgrade to a newer unit. I have the well documented issue of water in the oil (creamy sump oil on dipstick) which when drained was about 15% water. What is making this decision more difficult is that there is a brand new outdrive, trim pump assembly, gimble bearing and all associated bellows, seals etc also a reconditioned stater motor, shift cable, alternator belt, coil etc etc which was all done by the former owner in Feb this year.

The engine is not seized and turns over easily and there was no obvious water deposits in the cylinders or on the spark plugs.

I do not want to spend nearly as much as it would cost for a replacement newer engine putting this one right but if it worked out to be something simple it would be a shame to rip it all out.

I would be obliged for some help on the steps I should take in finding out where the water is coming from. How could I minimise the cost while investigating, just in case I eventually decide to replace it afterall should it be and expensive fix.

Thanks in advance

Tom."
 
"Tom, If you have no evidence

"Tom, If you have no evidence of water in the cylinders and good compression, you may like to have a look at my recent post under" CHRYSLER," It only took 3 years to fix" where my coolant was getting into the oil via a corrosion hole in the timing case cover, between the circulation pump and the timing case.

Just my thoughts, worth a check.

Ray."
 
"Thanks Ray, I'll take a l

"Thanks Ray, I'll take a look at it. How did you find the hole? I mean did you strip down and check all the possible faulty components until you got to the timing case cover or was there more science used.

Tom."
 
"Tom,
I was fortunate in that

"Tom,
I was fortunate in that I physically checked the oil and coolant before starting engine, which checked out OK. I let her idle while I went up front and cast off the mooring and by the time I got back in the chair she was going up to about 190f, and I turned off immediately, so there was no high revs and no overheat condition.

I knew the compression was good, and there was no cracks in the head or block, and I discounted a head gasket problem because there had been no overheats.

I talked to other guys and worked through mentally where the oil travels and especially where there is a close proximity of coolant to oil. The motor had to come out anyway, and with the Chrysler the water pump cover forms a common seal ( for want of a better word ) with the front of the oilpan (sump).

It was easier to remove the sump by loosening the water pump cover, which we removed, and there it was, abount 3/8" hole right through.

The funny part is that it was not gradual, fine one day and holed the next.

I consider myself lucky, but in hindsight and given the age of the motor (1976)it was an obvious place to look.

Hope this helps. Please keep us all informed of your progress, we are all interested and I for one am still learning every day.

Ray."
 
"Tom, there is a weep hole on

"Tom, there is a weep hole on the stbd. side of engine from the water pump. dripping would indicate bad water pump seal."
 
Thanks Scott I'll check th

Thanks Scott I'll check that out this weekend.

I have read in one of the manuals that condensation can be caused by a faulty thermostat leading to the engine running too cold. Interestingly the former owner reported that the engine temperature was 'erratic or non-existent' and that the engine 'keeps cold and the risers are cool to touch'

I will check the thermostat this weekend but could this really be the explanation for having 15% water in the oil pan or is that just too much for this to be source??

Tom.
 
It happens to granny's car

It happens to granny's car all the time when she drives it to church and back 2 miles each way.

In a 5 qt. oil pan that relates to 24 oz. or 3/4 of a quart of water. If you ran it w/a defective T'stat for 1 hour a day for 24 days it is highly possible for the engine to generate 1 oz. of water as a by-product of combustion since the engine has to be able to generate enough heat for the oil to vaporize the water.

Change the T'stat and the oil and filter then see what happens.
 
Guess what!? Ordered a replace

Guess what!? Ordered a replacement thermostat and removed the thermostat housing to check the exisitng one - no thermostat at all! I hope you're right Guy (thanks)and that this is the source of the water. I have replaced the oil but still get cream on the dipstick (not started the engine yet) how do I get rid of this or will running the engine clear it? and with the fresh oil in there also will it damage the engine??

Tom
 
A good MERCRUISER facility wou

A good MERCRUISER facility would tell you there is a problem in the intake / exhaust manifold area ( cracks )and where the carburetor bolts on.This is a common fault and it should take an experienced shop just minutes to check it out.These motors were not in the top 10 on the hit parade.
 
Tom:

London has a valid poi

Tom:

London has a valid point about the nature of your beast. The new T'stat and a couple oil and filter changes may not stop the "creamy" oil on the dipstick and the underside of the oil filler cap. What are the condition of the spark plugs? Run a compresssion check and report your findings. You may just need some new gaskets or need a new manifold assy.
 
"Guy thx for your guidance, I&

"Guy thx for your guidance, I'm borrowing a compression tester tomorrow and will report back. I did however get the motor started today and it ran pretty sweet until on increasing the revs it spewed out creamy oil from the rocker cover and the dipstick hole. Just like a crazy ice cream machine. I took out each of the plugs and they looked good - nice and dry with just a little soot but nothing too bad.

I drained all the oil and got around 10/11 quarts of liquid!? I was told by the guy who sold the boat that all the oil in the pan had been removed and so I just added the right amount to re-fill - maybe he hadn't drained it like he said? It was difficult to read the dipstick before filling as the creamy stuff was bunging up the tube.

Could the water get into the oil without going through the cylinders - as I say the engine ran great and the exhaust was not a all smokey."
 
"I really appreciate everyone&

"I really appreciate everyone's help - I think I'm getting somewhere.

Here's an update. It looks like freshwater is coming out of the oil pan drain hole even when the engine is not running. Today I noticed the reservoir was empty and when I re-filled it clear water dribbled from the oil pan and the level in the reservoir dropped. Looks like this will eventually all end up in the bilge.

Guy - yes I think my water pump is like the diagram although I haven't stripped it down yet.

Any further advice on this would be really welcome.

Thanks, Tom."
 
"Tom:

If you can borrow or

"Tom:

If you can borrow or rent a cooling system pressure tester from one of the auto parts stores in your area you can have someone pump the pressure up while you look and listen for the hissing leak. It is connected in place of the heat exchanger pressure cap.

If you can't figure it out, it's time to pull the water circulating pump apart, inspect the the mounting face and rebuild it. Let's just hope there isn't a crack in the water jacket at an oil return."
 
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