Overhaul?

[Unregistered]

I have a 1968 Tartan 27 with the original Atomic 4 – Model 5101, Serial # 194899. She is saltwater cooled. She has always been in the waters near cape cod. This means about four months of operations per year. I would guess on average she has consumed about 20 gals per year. So I guess that equates to about 20 hours per year for 36 years or around 1000 hours of use. I think it is fair to assume that the engine was flushed and winterized each year. I purchased the boat because she was well taken care of.

This engine runs great! She runs cool - 110 degrees at 5 knots, always starts, good compression, clean oil. New exhaust, carburetor, fuel filter, fuel pump ( electric), alternator, etc. most from your shop.

I do have some issues with the transmission, but I have not tried to do any of the recommended adjustments yet.

So she is rusty, but I keep her coated with Boeshield T-9 ( Boeing) to prevent any further degradation and that seems to be working.

My question: should I prioritize the overhaul of this old girl or not? What are the odds of a catastrophic failure at sea due to thinning piston walls or some other long term corrosion related issue? Have you seen these types of problems/failures in the engines you have rebuilt?

Any thoughts would be appreciated. I am trying to schedule an overhaul sometime within the next few years, but I have other issues I would like to deal with first.

[Don Moyer]

The serial number on your engine suggests that it would have been replaced during the late 70's. Atomic 4s from the late 60's had serial numbers in the 170,000's.

In any case, in the face of otherwise good performance and dependability, there is no reason to suspect that there is anything within the major castings of the engine that is about to fail, so I see no reason to rush to an overhaul. Reasons for an overhaul include: low compression (less that 70 psi on all cylinders), low oil pressure (failure to maintain 10 psi per 1000 RPM), blocked cooling jackets which do not respond to acid and/or pressure flushing, or a major mechanical failure (broken crankshaft, broken valve stem, etc.).

I would adjust the reversing gear (which is all that they usually require) using the procedures in Chapter 6 of our service and overhaul manual, and I would also recommend checking the thermostat. Your engine will operate considerably cleaner if you can get your temperature back up to around 160 degrees or so.