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Old 22-09-2016, 16:02   #1
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Compression Test for Volvo 2003

I'm seeking advice on the compression testing procedures for this engine. I have ordered a 17mm Bosch compatible dummy adapter injector (STATU-15-18A) and a gauge (STATU-15PB) that will go up to 1000psi.

BACKGROUND:After numerous overheating over the last few years, the power of the engine seems to be somewhat compromised. The engine will start up quickly with the cold start procedure but it's a more difficult if the ambient air is about 55f or below. Once started, even when warm, the exhaust is pretty stinky. There's no evidence of oil being burned but there is a little bit of gray/white smoke. The engine will go to 3200rpm and power the boat reasonably well but there seems to be less hp. BTW, the bottom is a racing Baltoplate bottom, and the fuel filters, water separator were just changed. Oh, no evidence of water in oil and vice versa.

My reasoning behind doing the compression test is to determine the state of the valves, rings, and cylinder head. I am planning on doing dry then wet testing of each cylinder. I've read to use very little oil when doing the wet test and to manually crank the engine a bit to wet the rings evenly.
Any suggestions or specific procedural advice would be most appreciated.

Thanks in advance,
Cant. Ben
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Old 22-09-2016, 17:22   #2
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Re: Compression Test for Volvo 2003

I am guessing that this will be a 30hp or 44hp engine either three or four cylinder?
Remove all injectors and shut off the fuel supply to minimise the compression load when turning the engine over on the starter motor. Test each cylinder in turn for the same amount of time spinning the engine over.
Compare each read out with the specification for the engine and comparison to one another.
The overheating is a symptom of restricted water flow through the engine for one reason or another. To establish where this might be you should eliminate the easy fixes first. The water pump is the obvious start point to ensure the impeller and pump body are in good shape. The water flow should be measured with a bucket and stop watch to verify what you have now and again after works that will effect flow.
That any heat exchangers are clean and not restricting flow.
The cylinder head is where most heat is developed and transferred to the cooling medium. Therefore in older engines this is a prime area for investigation. The waterways get restricted by deposits restricting the flow round and through the head passages, these can be cleaned out either mechanically if you are removing the head for valve and ring work or you can try the likes of "Barnicle Buster" or other chemical cleaners to dissolve deposits. Raw water cooled engines are far more prone to these deposits than fresh water cooled engines. Finally flow restrictions into the exhaust system need to be eliminated.
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Old 22-09-2016, 23:05   #3
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Re: Compression Test for Volvo 2003

Long time Volvo 2002 and currently 2003 owner. Assuming freshwater and saltwater pumps are functioning, first place to check is the mixing elbow, this is the most likely area to clog and create over tempo conditions.


Don't be fooled if you see adequate water discharge when running. Pull the unit and inspect, If necessary replace with new elbow and gasket.
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Old 23-09-2016, 09:05   #4
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Re: Compression Test for Volvo 2003

Acushla & Spotfire,

Thank you for your comments. The over heating issue has been resolved. The potential damage from the overheatings is yet to be ascertained.
The Penta 2003 is a 3 cylinder, 28hp engine. The workshop manual states the compression ratio to be 17.5:1 @ a starter motor speed of 2.2MPa (20-25kp/cm2).

Oh, and this is the Freshwater version.
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Old 23-09-2016, 13:35   #5
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Re: Compression Test for Volvo 2003

If your propped correctly you reach max rpms or just over at full throttle. If you could reach max rpms before it overheated & you reach the same rpms now then you are developing the same horse power that you were before it overheated. If you pull the injectors you need to replace the compression rings.
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Old 23-09-2016, 13:45   #6
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Re: Compression Test for Volvo 2003

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If your propped correctly you reach max rpms or just over at full throttle. If you could reach max rpms before it overheated & you reach the same rpms now then you are developing the same horse power that you were before it overheated. If you pull the injectors you need to replace the compression rings.
Scout, by replacing the compression rings, do you mean the copper injector sleeves? Yes, I thought that the same re the rpm and prop of my engine.

RE potential rpm, the engine will get back to the 3200 or so for a max cruising rpm. That's about the same as prior to overheating. It's hard to explain, but the engine just doesn't seem to have the same umps as it used to. For example, when motoring at 3-4 kts, if I carefully placed her in reverse (pausing through neutral for a moment) then gave a hard reverse thrust, I used to be able to nearly stop the boat dead in her tracks. I used to be able to cause everyone aboard to loose there footing. I can't do that any longer. Yes, she'll get up to rpm, but not quite as quickly as in the past.
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Old 23-09-2016, 17:23   #7
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Re: Compression Test for Volvo 2003

Quote:
Originally Posted by Capt Ben View Post
Scout, by replacing the compression rings, do you mean the copper injector sleeves? Yes, I thought that the same re the rpm and prop of my engine.

RE potential rpm, the engine will get back to the 3200 or so for a max cruising rpm. That's about the same as prior to overheating. It's hard to explain, but the engine just doesn't seem to have the same umps as it used to. For example, when motoring at 3-4 kts, if I carefully placed her in reverse (pausing through neutral for a moment) then gave a hard reverse thrust, I used to be able to nearly stop the boat dead in her tracks. I used to be able to cause everyone aboard to loose there footing. I can't do that any longer. Yes, she'll get up to rpm, but not quite as quickly as in the past.
They're the little washers. Regarding the lack of torque, maybe you have some growth on your prop.
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Old 23-09-2016, 18:33   #8
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Re: Compression Test for Volvo 2003

Compression test figures look good. The engine should run at approx 90C under all load conditions.
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Old 23-09-2016, 19:39   #9
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Re: Compression Test for Volvo 2003

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They're the little washers. Regarding the lack of torque, maybe you have some growth on your prop.
The 2003 does not have copper washers under the injectors. It does have copper injector sleeves.
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Old 23-09-2016, 21:41   #10
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Re: Compression Test for Volvo 2003

A warm engine gives a more accurate evaluation in compression testing. If you have dished pistons, use a piece of bent tubing so the oil goes to the rings, not fill the piston's dish. It doesn't take a lot of oil if you get it directly to the rings. If you use too much you may need to remove it before starting. Also, too much can raise the compression ratio, causing a higher reading than true. Worse case - hydro lock.
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Old 25-09-2016, 13:12   #11
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Re: Compression Test for Volvo 2003

RE: dummy adapter injector (STATU-15-18A), I have received this adapter and it doesn't look to be the same as a previously removed, old injector that I have. The adapter has two hold down slots and a much longer injector tip. The alternate slots do not seem to align with the body/length of my injector. Can anyone confirm that this is the correct adapter for these injectors? The 17mm diameter does seem correct.


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Old 25-09-2016, 19:07   #12
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Re: Compression Test for Volvo 2003

Here's a photo with an old injector, old copper injector sleeve, and new Lang TU-15-18 (M17 injector adapter).Click image for larger version

Name:	ImageUploadedByCruisers Sailing Forum1474852060.919573.jpg
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Old 27-09-2016, 12:32   #13
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Re: Compression Test for Volvo 2003

Can anyone advise if one must replace the pressed in copper injector sleeves once the injectors are removed prior to re-assembly to insure a good seal? Before I attempt this compression test I want to determine if I need to have the special tools and parts available for a proper re-assembly.
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Old 27-09-2016, 12:34   #14
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Re: Compression Test for Volvo 2003

Quote:
Originally Posted by Scout 30 View Post
They're the little washers. Regarding the lack of torque, maybe you have some growth on your prop.
Bottom and prop are clean!
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Old 27-09-2016, 14:22   #15
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Re: Compression Test for Volvo 2003

Quote:
Originally Posted by Capt Ben View Post
Can anyone advise if one must replace the pressed in copper injector sleeves once the injectors are removed prior to re-assembly to insure a good seal? Before I attempt this compression test I want to determine if I need to have the special tools and parts available for a proper re-assembly.
The injectors are designed to be removed without having to change out the injector sleeves. If the injectors have not been out for a long time, then it is a crap shoot. Small fuel leaks can erode the sleeves. Small coolant leaks can corrode them. Either one may require a new sleeve. In some cases yanking on the injector has pulled the sleeve with it -- which will dump coolant into the cylinder. So be a little gentle on the removal.
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