Logo
FULL SITE MENU

AQ130/250 questions

A

Andur

New member
Hello.

Last year I got myself a new/old boat with an AQ130 engine and 250 stern.
The boat itself is a NORCEM 21 (DC?)
Had a broken camshaft and a clogged cooling.
Took it apart, cleaned, inserted new camshaft, new sparkplugs, new impeller. It has an electronic ignition built in, checked the timing, its ok.
The compression was also ok for an old engine (175 PSI).
Also cleaned the carbs (2 Zenith-Stromberg)

Now I have a few questions, problems.

1. At WOT the revs go only up to 4000-4100 (manual says cruising speed is 4600'ish)
2. Speed according to GPS is 25 mph max

Otherwise the engine is starting like a charm, cold or warm, doesnt stutter or anything.
The prop has some wear, but i dont know what ratio prop it is. The seller said its the original for this stern/engine, but i dont know.
Also it has an oil leak near the flywheel, i guess a faulty seal at crankshaft?
Engine temp at top of the engine was about 100 C. Block was about 90 C. Is that too high? (laserthermometer)

Anyways, I think it is a good old engine, now I just need some advice on how to make it purr a bit better.

Thank you.
 
Possibly not a lot of engine for a lot of boat, depending of hull deadrise and superstructure...

re: Manual saying "cruising speed is 4600ish"...
I didn't look up the manual, however manuals usually specify MAX WOT which is NOT cruising. Max cruising is usually about 80% (or less) of MAX WOT,where WOT = Wide Open Throttle.

re: Engine temp.. WAAAAAAAY too hot. Then again sounds like an overpropped engine ( working too hard) and running too fast, especially if a new impleller. If in sea water and raw water cooled should see no more than 140 F ( 60 C) vicinity. If it has a heat exchanger, should be about 160 to 165F ( 71 C) . Volvo engines subject to running hot due to degraded water neck ( where the water hose connects to the drive itself), i.e., pin holes for a vacuum leak wherein the engine is sucking air in addition to water.

Before fooling with the prop and verifying the drive ratio... Status of: cap, rotor, wires, freshness of fuel, condition of boat bottom????

Re: Broken cam... I'm not an experienced Volvo mechanic (like Ricardo for example), but those aren't fragile engines... a broken cam??? Wow!
 
Last edited:
Well english is not my primary language so maybe a few misunderstandings there.
by manual max wot is set to 5100, max cruising speed 4600
Engine temp: i was not there when my brother took the readings, might be something off there. On the dashboard gauge it is just in the red zone.
And the camshaft was not broken in half but one of the cams was worn down to zero.

bottom of the boat is clean, no unusual unevennesses, no cracks. Fuel is 2 weeks old. Wires might need a bit of overhauling. Cap and rotor seem to be fine.
Today I took the carbs apart, cleaned, and the engine seems to run a bit better, but still 4000-4100 revs. I was alone in the boat, and the fueltank was 1/4 full.
 
There could be quite a few factors affecting WOT. It's not unusual for an older boat to be hauling around some "water weight" from waterlogged foam or wood. Would be a good idea to check for dry rot in the deck and transom.

As for the temp, any place that will allow air to enter the suction side of the raw water system will slow or stop water flow. As sandkicker mentioned, the water neck fitting (the Volvo term for the hose connection on the outdrive) is considered a wear and maintenance item. They corrode from the inside so it's hard to tell when they start leaking. But any hoses or connections that can draw in air will cause problems so you need to check everything as a system.

Good luck with it. Older boats can be a great source of accomplishment and enjoyment when you get them running right.
 
If you can't reach the spec'd 5100 rpm under the conditions you describe, you have a problem. Multiple problems if you include the too hot condition. First priority... find the cause of overheat, preferably @ no more than 3000 to 3600 rpm for now.
 
Back
Top