Hi,

Sorry my Swedish is not that good so that is why this email is in English.

In August I bought a Coronet 21DC with an AQ170/280 engine from 1977. Although the engine still works, there are few issues with it. Cooling water is dripping from the small vertical pipe on top of the oil cooler (one rubber sealing seems to be deteriorated) and there seems to be an oil leak to the cooling system. I noticed this when I started the engine as oil appeared near the exhaust and when I opened the cooling jackets to get the cooling water out I noticed that grey oil was coming out the cooling jacket at the bottom of the oil cooler. I do not know whether both issues are related (btw I guess they are not). The motor has been running fine after I bought it but the boat has not been used for while before I boat it, so things have become old, e.g. it could be anything, gasket, oil cooler etc.

Now I need to take a decision whether I go for a complete overhaul of the current engine (still my preferred option) or replacing it with another engine (preferably diesel, e.g. cheaper running cost and more safe).

What I would like to understand what the views are of the other Coronet owners, so
- What would be your advice, a complete overhaul of the current engine or replace it with a diesel, and what would be the decision points?
- If I decide to replace the current engine, what would be the best replacement options (cheap and with minimal adjustments to the original design), anyone has got a few experiences with this.
- What would be roughly the cost for a complete overhaul of the engine, so it should be almost as new and how to I decide on the right dealer?

Any advise with regard to the above is really appreciated!

Thanks in advance,
Michiel Steltenpool

I would replace the old Volvo AQ 170. The engine is old and has a very small value on the market.
Instead I would get a V8 petrol engine complete with a 290 outdrive with powertrim and DP.

I know some members have bought diesel engines but I expect that to be much more expensive.

I think it is almost impossible to give you a good answer. I mean the cheapast way to go is to overhaul your engine or swith to another AQ170 in a better shape. Swithing to a newer V8 with a complete 290 outdrive will higher the value on your coronet but also cost a lot more. Switing to a Diesel engine is even more expensive but could be a good alternative. I think you need to decide how long you are planing to keep your boat and how much you will invest in your coronet. One other thing to consider is how much you are using your boat every season.

Regards,
Ulf

Hi Michiel,
There has been a number of "strings" in this forum discussing just your subject, but since you state that your Swedish isn't that splendid, I'll share some own experience with you in English.
Two years ago I was in the process of replacing my old V6 175 hp (VP175A/280) and as you know there are a number of options that would fit the 21 DC. After a lot of evaluation, my decision was to to get a smallblock V8 with DP and powertim, and I was fortunate enough to find a complete drivetrain (VP570/290DP FWC) in condition like new (<200 hrs). Performancewise it's outstanding with a silent cruising speeed of 27-30 knots and top speed of 43-44 knots. On top of this the 275 hp also delivers a torque that makes the boat almost insensitive to load. Looking at the financial side, I would say that provided you find the right stuff this is really value for the money.

Good Luck!

Best Regards
Magnus

Dear Michiel,

I will join the others in recommending that a V8 or a modern V6 is really a much better fit for the boat. I have a Volvo 225 V8 in my DC, and it works splendidly. A couple of observations:

- Although there is a growing sense of "preservationism" dictating keeping the boat original, there are two obvious exceptions from where it is sensible to keep your Coronet original.
1: Fuel tank. The old galvanized tank will be compromised and dangerous by now if it has not been replaced with a modern one. Either alu or stainless will do the trick.
2: Engines. Technology has moved on, and it is widely accepted to replace the (too small) original engines with something better up to the job.

- The 21DC is a fantastic boat, but it was never equipped with "Proper" engines when new. Neither the B20 nor the B30 (AQ170) engines were capable of providing the oomph which makes a boat like the 21DC excel. I would say a minimum of 200 horses and a good helping of torque is required (of course, "required" is very subjective).

- While diesel is economical to run, I would state that it is less in keeping with the spirit of the boat than a petrol one. I'd go for the song of a petrol V8 any day.

- A diesel conversion is much more costly if you want a reasonably new engine. There are plenty new-ish petrol V8's available at reasonable prices.

- As mentioned above, you add greatly to the value of your boat if you do a proper engine/stern drive upgrade rather than refurbishing your current B30 engine.

Enjoy your project!
Lars

What is the expected cruising speed and top end speed for a 21dc with aq170 engine?