Looking for help

[tide me over]

can anyone really tell me what is so wrong with the 170 Merc 3.7L engine. I have heard so many people say stay away but, they could not really tell me why!

 

[HT32BSX115]

Re: Looking for help

Uh.....

Ok, if you did NOT buy one....... DON'T

The 3.7 in it's various forms is a dinosaur. Mercury screwed the pooch as it were..

It's an aluminum block 4 banger with a Ford 460 head. (anything associated with a 460 cannot be good!!!)

It also has other problems....alternator, cam driven water pump. (Some models) had too small a heat exchanger in the cooling system.....

they dumped it ....It's not made anymore.......


I'm sure there's more.....



Regards,


Rick

 

[jerryjerry05]

Re: Looking for help

The motor itself ran good it just had a few problems like Rick said.If your mechanicaly inclined and can replace the bad items it will last a long time.
Most problems come from the cam seal on the water pump(fixable).
I have one in a 21 Thompson and it runs good. Jerry

 

[tide me over]

Re: Looking for help

thanks for your comments, yes I have one in my current boat and it runs very well. I've owned this boat for about 10 years and it is a 1986 powerplant so, I thought I would ask to see what to look out for as I have had no real problems with it all this time. Thank you again!

 

[Tom Sherwood]

Re: Looking for help

I have had every problem one could have with this engine. Then again I have had it since 1985. The worst thing you can do is over heat it. Get a manual and do the maintainance.... religiously. Parts are getting hard to find. Some are out of production. Like the water pump cover. I over tightened a bolt and cracked it had to get it welded. All in all, Great on gas, great power plant for a 4 banger. I got my moneys worth.

Cheers

 

[tide me over]

Re: Looking for help

Thanks Tom, I have already replaced the waterpump in the drive and has not fixed my problem. I'm still overheating while at plane or WOT. I don't want to overheat this aluminum block so I will keep diagnosis going. anything you have to add would be great.

 

[bhammer]

Re: Looking for help

Thanks Tom, I have already replaced the waterpump in the drive and has not fixed my problem. I'm still overheating while at plane or WOT. I don't want to overheat this aluminum block so I will keep diagnosis going. anything you have to add would be great.

Do you have the 3" or 4" heat exchanger? The 3" exchangers were prone to heat up at WOT.

You may want to remove the end caps of the exchanger and look to see if they are gunked up. You can take it to a raditor shop and have it flushed. Make sure you have the correct antifreeze mis as well. Also check that you have the correct thermostat installed. Have you ever had a drvie impeller (water pump) go bad and not find all the peices? If so, some may be lodged in the cooling system somewhere.

Just a couple thoughts....

 

[Tom Sherwood]

Re: Looking for help

Have you checked the empeller on the I/O?

 

[tide me over]

Re: Looking for help

After much blood sweat and tears it looks like the elbow from the riser is clogged. One of the only parts to my engine that is cast iron. I will let you know if this fixes this problem. I have replaced the waterpump in the drive, pulled apart the front of the engine to check the connection from the cam to the circulator pump, checked the coolant, checked the t-stat, checked my gauge in dash.... I have no other ideas and this damn part is expensive now that I've found that it clogged up with rust, I have to replace it. I hope that this clog is the reason for the overheat while at cruise. My threory is not enough hot water to escape overboard and that is why I run hot off idle. this is becoming an expensive summer season...