compression test

Sorry guys wanted to ask a question and went to wrong page, here it is, I want to khnow if by doing a compression test would be able to khnow if there is a head gasket leak to the water jackets?

I will answer a question with a question. First, what kind of problem are you experiencing?

My starboard engine runs hotter than port under load right after 2200 rpm,always lots of steam and high temp. over 185. at low rpm temperature is ok with minimum steam. Port side engine has no steam at all and temperature keeps around 160.
I just installed new elbow risers and that was needed old ones were more than four years old and looked bad.
Heat exchanger were cleaned and put back, raw water strainers ok, hoses ok.
Only member of the cooling system not touched yet is the oil cooler, but I will go there this week.
I wanted to hear your opinion because my mechanic says that the u cooler is not responsible for the overheating and steam, he is more like betting tours a head gasket leaking to the water jackets.
I want to make sure ,I cover all the bases before going deep down the engine. Your discusions over this forum is very helpfull, I think will do a compression test and clean oil coolers. I've read before than a low even compression in two adjacent cylinders indicate a head gasket leak. Any ideas from you guys is appreciated, thanks

Before you jump into a compression test, the water delivery system needs to be checked 100%. When was the water pump inspected last, when was the last time it was rebuilt? Pulling out the water pump impeller and saying "It looks good" and putting it back in does not constitute a rebuild of the pump. The U cooler if clogged with old anodes will restrict water flow and cause an over heat.

Is there a restriction in your exhaust? This will cause the same problem.

Ditto Chris.

Also, your engines are equipped with Closed Cooling systems if I read it correctly.
If this steam is a result of head gasket failure, your coolant level is going to be affected.

Any noticeable difference is coolant level????

Any noticeable excessive expelling of coolant from the H/E into the coolant recovery reservoir as RPM is quickly increased????
We're not talking about heat expansion expelling...... we're talking about cylinder pressure that may be escaping into the cooling jackets that would over-pressurize the H/E system.
Test this cold and again while warm.

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I'd suspect the raw water system, too. Pump and oil cooler are the top two on the list 2-B-Checked.

The answer to your original question is No, for a small leak. Best approach would be to use a cooling system pressure tester.

Hi guys thank you all for your advise, you nailed it. just had the oil cooler acid bathed today and put it back and boom just like magic went out for a test and my temperature right on at 160 just like my port side engine, no more steam coming out, only at high rpm but very small amount, normal.
I also did compression test on that engine and one side shows three cylinders with 120 and one at 115, the other side ofthe engine is 135, 140, 140 and 148. Maibe I should keep watching or what you guys think?
Thank you all again.

How many Hours on the engine? And what size engine is it?

I will do the comp. test over again, you are right about the way it should be done. the plugs were not pulled out all at once .
About the age of the engine, it has 580 hrs, 2003, installed in 2004 brand new, 350 fwc 5.7 cdi 270hp, holly carb. hurth 5000 tranny with vdrive.

Pull all the plugs, disconnect the ignition system, push the throttle wide open and then take a reading. After you have tested all cylinders and you find the numbers to be low, squirt a little oil in each cylinder and test them all again. If the compression increases with the oil, chances are the rings are worn, if no increase, chances are you have a problem with the intake or exhaust valves.

Thanks Chris that's just what I will do had and will get back to you, thanks

Ah.... the ole oil in the cylinder trick. There's a caveat to this, IMO...... actually, several!

One... the oil volume alone will raise the cylinder pressure all by itself, because it occupies space/volume.
To do this accurately and scientifically, and/or for a comparison.........., the same quantity of oil must be added to each cylinder.

Then there's the V engine and/or slant six.
Oil in the cylinder of a V engine will tend to pool at the low point of the cylinder, rendering an uneven wetting of the ring landing.


Then you add into the mix, the full dished pistons that we typically find in the OEM SBC today.
How much oil ends up in the dish, and not at/on the ring landing???

While it sounds like a good science, it's not always so.

I think the where this originated was back in the days of the vertical cylinder in-line engines and flat top pistons.
In that case, the oil test may have proved to be more beneficial and accurate.
When we carry this over to the V engine and dished pistons, the results may not be the same.

Just say'n!


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RicardoMarine said:

Ah.... the ole oil in the cylinder trick. There's a caveat to this, IMO...... actually, several!

One... the oil volume alone will raise the cylinder pressure all by itself, because it occupies space/volume.
To do this accurately and for a comparison....., the same quantity of oil must be added to each cylinder.

Then there's the V engine and/or slant six.
Oil in the cylinder of a V engine will tend to pool at the low point of the cylinder, rendering an uneven wetting of the ring landing.


Then you add into the mix, the full dished pistons that we typically find in the OEM SBC today.
How much oil ends up in the dish, and not at/on the ring landing???

While it sounds like a good science, it's not always so.

I think the where this originated was back in the days of the vertical cylinder in-line engines and flat top pistons.
In that case, the oil test may have proved to be more beneficial and accurate.
When we carry this over to the V engine and dished pistons, the results may not be the same.

Just say'n!


.

Click to expand...

Doing the oil test, we are not looking for an accurate reading just a major increase. The test can be done with 5w oil in a atomizer. That is what I use. When you spray it on the plug holes it hits the high side of the cylinder and coats pretty much the whole top of the piston.