The Mercruiser 470

[bigkahuna427]

I have read about this engine and everyone says stay away. This is the one with the alternator on the crank and no belts. Just looked at a Wellcraft in nice condition with one of these in it. It did have a very attractive price of course! I know everyone is going to say stay away. BUT, what are the major problems with these? How are the circulator and raw water pumps driven? What is the automotive equivalent to this engine? I am a retired Master Auto Tech so give me the list.

 

[Eric 3.7LX Alpha 1]

There is no automotive equivelant, it is designed by Mercruiser. It does use Ford 460 parts though, Crank, pistons, rods, bearings, head, valve train. The aluminum block, camshaft and timing chain are Mercruiser.

The problems:

The factory charging system works well when it works, the common issue is the the voltage regulator fails and output is at over 15-volts. The common fix is an aftermarket belt driven alt.
to be continued....

 

[Bt Doctur]

the Merc 470/488 motor is a bastard creation from merc. no brothers or sisters ,not even an orphan. a creation. 1970 Maverick flywheel, 460 head, 460 pistons, 302 rods and bearings(I think) .Major issues are the 3 inch heat exchanger. 4 inch upgrade is recommended. Engine circ impeller(not pump) driven by the camshaft.
Raw water feed comes from the impeller in the lower part of the outdrive.
Never an auto motor.Good horsepower to weight ratio. Some run these motors on the circle track circuits too.

 

[wrestling coach]

Rule 1- Never overheat this engine. Iron head/aluminum block expand and contract at different rates and the head gasket blows. Keep a fresh impeller in it.
Rule 2- Always observe rule 1
Problem 1- 3" heat exchanger, if you have one, should be exchanged for a 4" exchanger. 3" is just too small and 4" works sooo much better. Problem 1 solved.
Problem 2- Charging system ( stator/regulator) is troublesome. Replace with alternator conversion kit/brackets. Ezzy-Pezzy Problem 2 solved.
Problem 3- The most annoying. Coolant circulating pump for the block is run off the cam snout. Two seals in the cover to that pump run on the cam snout and over time run a groove in the cam snout and can allow coolant to leak past and into engine oil. There is a drain in that cover to warn you in advance that a leak is occurring. This is a pretty big repair. Speedi sleeves applied to cam snout new seals in the cover. Problem 3 solved.
The engine coolant pump circulates coolant through your block and into a series of tubes in the heat exchanger where the engine heat is removed and returned to your block. Lake water is pumped through the lower unit by the impeller and into the heat exchanger pulling the engine heat out and then returns through the exhaust and back to the lake.

Dennis

 

[stonyloam]

If you know your way around a engine, no problem! The coach hit the high points. Yeah ya gotta keep it cool. The 3" is OK IF you change the impeller every other year. It is adequate but there is no room for error, or a worn impeller. The charging system works fine, the problem is when the voltage regulator goes, it is EXPEN$IVE, so most folks go with the alternator kit when the regulator fails, until it fails,keep it. The cam seals are a pain, but about a long afternoon job. Keep an eye on the weep hole, make sure it is clear and if you see any AF leaking then it is time for sleeves and seals. OK now for the good stuff. When you get it running right it is a strong,powerful and economical engine. Best of all it is a snap to winterize. Wit the block full of 50/50 auto antifreeze all you have to do is pull the aft seawater drain plug on the exchanger and you are done. I do mine right on the ramp when I pull it for the winter, about 5 minutes and never a cracked block in the spring.

 

[bigkahuna427]

A lot of the boats I have been looking at with decent price have this motor in it. I should assume having this engine decreases value given the bad press. That "regulator" I found on Ebay and with the cooling pipe thought it might also contain the rectifier? If the rectifier were integrated into the regulator that is probably why nobody was suggesting a regulator re-fit.

I assume when you guys say 3" versus 4" exchanger this is the diameter?

When you say 460 engine parts are you talking Ford 460 like automotive? What is the displacement?

 

[Eric 3.7LX Alpha 1]

Yes the exchanger size refers to the diameter....It uses the Ford 460 pistons and head. 224 cubic inch, 4.36" bore. 3.75" Stroke

 

[stonyloam]

There are basically two versions of the 470. Old, pre about 1981, and new from about 1982 here is what the "new" design reservoir looks like: https://www.mercruiserparts.com/Sho...=EXHAUST+MANIFOLD+AND+EXHAUST+ELBOW(ALUMINUM) as far as it goes the later the better. They changed to an aluminum exhaust manifold in the mid 80's. All of the "new" design engines have 4" exchangers. Yeah it is a ford 460 head that has a water inlet bored in one end. Uses the 460 pushrods th set valve lash too. Yeah the bad rep will help lower the price, but I would buy another one in a minute.

 

[bigkahuna427]

No Title

This motor is in a [FONT=arial, helvetica, sans-serif]'85 Wellcraft Steplft V-20. Here is a photo. The engine looks to have an alternator mounted low and what looks like a 4" heat exchanger. How do these do in salt water? I assume raw water passes through the exhaust manifold. What do you guys think?

I guess I have been staying away form this engine but it sounds pretty [/FONT][FONT=arial, helvetica, sans-serif]manageable. At the price point I have been looking and with every boat having some issue or ISSUES maybe this is my niche?[/FONT]

 

[bigkahuna427]

No Title

 

[stonyloam]

Yeah the raw water exits the exchanger and travels up through a hose to the exhaust elbow, so the salt water only touches the exhaust. I think Eric runs his in salt, so he would know better than me about how long the elbow will last. It has a full system, so the exhaust manifold is cooled by antifreeze, not raw water.

 

[achris]

I had a 4.3 V6 with freshwater cooling, and ran in salt water. The engine is now in a friends boat, and at 20 years old is still doing fine. The heat exchanger gets removed and taken to a radiator shop every 3 or 4 years for cleaning, and that's the entirety of the maintenance on it.

If you are confident with engines, and can tackle any work required yourself, then this engine in a well priced boat might be just the ticket. I know a lot of people say run away from this engine, but I actually like them. Yes, a few design flaws, but overall, a good engine, reliable, economical (which, btw, should never be a major factor in buying a boat) and great power to weight ratio. With an alternator kit and 4 inch HE, pull the front off the engine and sleeve the shaft for the seal for the water pump and your set to go.

Just my 2 cents.

Chris........

 

[vincechig1975]

I rebuilt my 470 two years ago and I haven't had any issues with it. I transplanted it into my Smoker Craft ,replacing the 120 that was locked up. Runs Great ,thankfully I had the matching out drive that was on the cuddy that was scrapped and worked a little magic of my own without sacrificing safety of my riders ,wow you outta see her fly across the lake now. Great motor as long as you take care of it.

 

[MikeAustin]

I have recently had service done on my stern drive
The mechanic was concerned about a noisy timing chain rattle and suggested replacing the chain and the tensioner on my 470 Mercury
i have had the boat for five years and there has always been a rattle at idle but once I’m cruising the rattle is not noticeable and the engine runs great
i have looked into replacing the timing chain and tensioner but parts are NLA
should I be concerned about this
your thoughts or positive input appreciated

 

[GA_Boater]

I have recently had service done on my stern drive
The mechanic was concerned about a noisy timing chain rattle and suggested replacing the chain and the tensioner on my 470 Mercury
i have had the boat for five years and there has always been a rattle at idle but once I’m cruising the rattle is not noticeable and the engine runs great
i have looked into replacing the timing chain and tensioner but parts are NLA
should I be concerned about this
your thoughts or positive input appreciated

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