MerCruiser 190

A friends looking at a 1985 Searay 250 Sundancer. This boat has twin 4 cylinder MerCruisers. Does anyone know who makes these engines? They're dang big 4 bangers and put out more power than a lot of sixes. Could be a fun old boat with 380 horses, most this size have the single 260hp V8

Re: MerCruiser 190

They are a version of the Mercruiser 470. Went by different models depending on the year.

They have lots of torque due to the large bore. It has the cast iron head and bore of a Ford 460, but Mercruiser designed alum. block. They all have closed cooling, which makes for easy winterizing, but do have the following issues:

-Engine circulating pump is bolted to the front of the camshaft and has 2-seals that keep the water and oil separate. Those seals can wear a groove in the cam and cause the engine to weep water at the front cover indicating a problem. The fix is a new camshaft or speedi sleeves and new seals. (repair is discussed in the link below)
http://www.sterndrives.com/470information/470coolantleakrepair.html

-Engine can blow head gaskets easily if it overheats, so make sure there is a good temp gauge and stay on top of maintenance with impellers.

-The factory charging system uses a stator in front of the crankshaft and external voltage regulator. The voltage regulator is very expensive and are a known issue. The best fix for it is an aftermarket belt driven alternator kit.

Re: MerCruiser 190

The engines are a Mercruiser design. Aluminum block, open deck design, using a Ford 460 head. Commenly called a 470. They were used by Merc from 76 to 89.
The open deck design means you can just about bet money if you have an overheat, you will have to replace the head gasket.
The charging system is designed like an outboard with a stator (under front pulley) and a rotor (front pulley). Some of the charging system parts are no longer available, those that are, are very expensive. Most people replace them with an alternator kit with mounting bracket when the charging system fails.
Another problem is the front water pump seal failure due to grooves in the cam. This allows antifreeze into the oil.

When they do run good, they have a lot of torque and HP for a 4 cylinder. There are lots of them out there running, but it's helpful to enjoy work on your own engines and keeping up with maintenance on these engines.

Before you ask, converting to a V6 on that boat isn't going to happen, the engines are mounted too close together for V type engines.

Re: MerCruiser 190

Thanks for the info Eric. It'll likely scare him off from buying it though. Nice boat and it has only 400 hours on it.