Low hours 470 Engine ?

[Rake722]

Hi all,

I have a Draco 1800 fitted with a 1978 470 motor of unknown history and hours.

I've fitted the later alloy exhaust manifold, new elbow, Pertronix ignition, alternator upgrade, new sierra starter, and rebuilt the carb and 4 inch HE

she has never given me much trouble aside from an overheat that may have been a false alarm as I replaced the sender and gauge with ones that my not be compatible and it triggered the high temp alarm a few times, but she has never boiled her coolant.

I plan on shipping this boat to the Greek islands for family pleasure during our 3-4 week holidays there in summer. She would get more use there in 3 weeks than here in the UK in a year.

I have found a motor with only 66 hours on it that is a 1979 engine identical to the one I have. The 66 hours are genuine as the engine comes with the original gauges. It also looks like nearly new.

Plan would be to graft all the upgrades from my existing engine on to the low hours unit, and fit it to the jalopy before shipping the boat to Greece.

The price of the 470 is $1100 making it highly attractive as opposed to a 4.3 which would cost more like $5000 over here.

I plan to have the engine compression tested of course.

Am I going to silly lengths here or is this a well founded move ?

with engines here being rare I think its a no brainer but just wanted to ask your opinions.

Images are of the low hours engine.

 

[stonyloam]

I would do a compression check, make sure your coolest level is good, change the oil and the impeller, take it for a good long test run, and if it is running well, ship it. The other engine may only have 66 hours on it, but the cam seals could be bad, and if it has been sitting for a long time you could run into all kinds of little nagging problems, oil or coolant leaks valves could stick or rust in a cylinder or even a head gasket on the verge of failure. I would buy it as a spare, then get it running and make sure all is well with it, then should you have a serious problem, switch it in. Mine is an 87, had it out this week and it ran perfect, so if yours is running well go with it, just IMHO.

 

[Rake722]

Thanks Terry,

Advice appreciated. I'll almost certainly get the low hours unit, question is as you say - whether to fit it right off or get it running on a bench first and keep as a spare.

Do they all suffer from the cam seal issue or are there those who dont ?

 

[Scott Danforth]

Do they all suffer from the cam seal issue or are there those who dont ?

All 470 motors suffer from the cam seal issue. they also suffer from head gasket failure due to the floating bores. there is a reason Mercruiser abandoned the motor

 

[stonyloam]

Yes eventually the cam seals will fail. If you buy the spare, with that old of an engine and it sitting most of its life, it would probably be a good idea (even with only 66 hr) to go ahead and change them while the engine is out. The head gasket is likely to fail if the engine is overheated, and can fail for no apparent reason too. That is why it is a good idea to do a compression check once a year, and change the impeller every other year. I don't think you can go wrong by buying that other engine.

 

[Scott Danforth]

changing the head to an aluminum head will help with the head gasket issue, however the floating bores are still a problem. (its a slightly modified Ford 460 head)

a speedy sleeve on the cam fixes the cam issue (non-hardened cam nose)

 

[kenny nunez]

As mentioned along with the head gasket and cam/water pump seal repair the electrical charging is also a problem. There is a after market conversion to install a "1" wire Delco alternator to the front of the engine.

 

[nola mike]

He already has the alternator. I wouldn't trust my vacation to an unknown 30 year old motor. make sure yours is in good shape and run it. You're much more likely to have something else fail than a catastrophic engine failure. And fwiw, I still haven't had a hg failure or cam seal leak.

 

[Rake722]

Nola, thanks but that is the question.

The engine I have now came from somewhere unknown and has unknown hours and history, surely the 66 hour engine will be less of a question than the one that is installed ?

 

[Bondo]

The engine I have now came from somewhere unknown and has unknown hours and history, surely the 66 hour engine will be less of a question than the one that is installed ?

Ayuh,.... They're both still 30-odd year old motors, rebuilt by "Somebody" usin' used parts with fresh gaskets, 'n what-nots,....

'bout the Best way to know any motor's general over-all health is with a compression, 'n leak-down tests,....

The unknown motor mighta just been built by a Pro-Mechanic, 'n barely broke-in,...
The 66 hour motor mighta been built by a 16 year old kid with no mechanical knowledge,...

 

[nola mike]

I assumed that even with unknown history that you have used yours, and know that there aren't any pressing issues. Again, if I swapped in a new engine, forget about used, I wouldn't count on everything running perfectly right away.

 

[Rake722]

Thanks guys, points duly noted.

I'll consider my options here.

Nola - Yes I have used my existing motor some 15 times 20 miles per journey and the high temp alarm sounds but no boiling of the coolant - may be a false alarm.
I have fitted a thermo couple pt100 type in the second sender hole and am waiting for a gauge to arrive so I can compare the sierra gauge and TMP sender to the thermo couple and IR to determine if it s a false alarm or not.

I've installed the 4 inch HE too.

Also the later EM which I assumre must have a new thermostat in it.

Aside from that she has not had any issues.

As for the 66 hour motor - if I install it I will give it some water time before shipping to Greece.

A friend over here is a marine engineer and he would use the 66 hour over the existing.

 

[Rake722]

Compression check done -

Pot 1 - 121PSI
Pot 2 - 122PSI
Pot 3 - 125PSI
Pot 4 - 124PSI

Looking god - bought engine.

 

[2fishy4u]

I would investigate that high temp alarm, you dont need these engines to "boil" over" to blow the headgasket. Mine blew at 200, and it did not steam, or boil over. If its running over 165 there is a issue. And it will get worse fairly fast from my experience. I have had the boat almost 3 years now. Replaced both engines already, One had number 4 cylinder burned to a crisp. Turned out the gauge was bad and not reading the overheat. I test my gauges every week before going out now. The other one broke a piston rod..... I have so much faith in these motors, I have a spare waiting in the garage. They are awesome when they are running right, but they can go south fast when they are not.

 

[QBhoy]

A few years ago...a friend of mine had the same or similar situation to you.
Original engine was a 470...nags of get up and go and decent on fuel...it then suffered the usual issues and was eventually scrapped after a few water pump shaft seals and cylinder heads skimmed.
Found another in mint condition. 6 months later...same issues. Tried to repair, worked for a while and eventually gave in.
He replaced it with a 3.0 Merc. Best thing he could ever have done. Straight replacement. No messing with mounts or drive ratios.
Sure it's not as powerful, but it's not a million miles off it.
Good luck.

 

[Rake722]

Well its just as well I just bought a get me home engine too.

I'm in balls deep now so going to go ahead and whip the engine out and install the newer one.

While the old one is out I'll rip it down and see what I can find.