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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 16208
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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Are all 1988 3.0L Mercruiser 4 cylinder engines LH? Water

Customer Question

Are all 1988 3.0L Mercruiser 4 cylinder engines LH?
JA: Sometimes things that you think will be really complicated end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so the Marine Mechanic can help you best.
Customer: Water pump rotation is said to be the same as engine rotation. My boat pump(new) is not moving water so is it possible the wrong kit was installed?
JA: Sometimes boat issues seem like they'll be really complicated, but end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the Marine Mechanic should be aware of?
Customer: I pulled the thermostat out with no effect.
Submitted: 2 months ago.
Category: Boat
Expert:  Jason replied 2 months ago.

Hello my name is***** engines are LH rotation. What kind of problem are you having, are you having an overheat issue?

Customer: replied 2 months ago.
With muffs on temp runs 140ºƒ but immediately over heats in the lake.
Expert:  Jason replied 2 months ago.

Has the seawater pump impeller in the sterndrive been changed yet?

Customer: replied 2 months ago.
The omega 1 version*****pump including the pump plate and two gaskets, new impeller and impeller housing are new with the impeller blades set-up for clockwise rotation as shown in the Mercruiser manual.
Expert:  Jason replied 2 months ago.

Is the engine actually overheating, did you double check the engine temperatures manually with a temp gun in order to make sure that it was actually running hot?

Customer: replied 2 months ago.
Temp. gauge is correct as verified with an infrared temperature gun.
Expert:  Jason replied 2 months ago.

Okay what kinds of questions did you have for me on the issue? Did you have questions that you wanted me to answer? Or did you just want to have a conversation about the problem?

Customer: replied 2 months ago.
What could prevent the pump from moving water considering the engine and water intake ports to be super clean, like my overlooking or missing something in the housing below the impeller?
Expert:  Jason replied 2 months ago.

All overheats happen for one of 5 reasons, and these are the reasons from most likely to least likely.

1. Water is not getting in - bad seawater pump/impeller. Or a clog in the water line in the transom between the sterndrive and engine

2. Bad thermostat

3. Water is not getting out because of a clogged riser and or manifold

4. Water is not circulating - Bad circulation pump

5 Water is getting airbound - On some engines that can mean a head gasket issue, but that's not common with 3 liter engines. But what is common on the sterndrive is the water pocket grommet can dry rot out causing the copper water tube to have a very loose fit where it presses up in to the upper portion of the sterndrive.

That being said. What you want to do first is put the boat in the water. With the boat in the water disconnect the main water line that goes from the transom to the tstat housing and disconnect it at the tstat housing itself. Start the engine up and once the water starts coming out aim that hose into a 5 gallon bucket and run the engine at idle for 15 seconds, and then turn the engine off. In that time frame you should have at least 1.5 gallons of water. If you do not either the impeller is bad or the water pocket grommet for the water tube is bad. If you do get good flow, normally you would change the thermostat and retest, but you already did that. So step 2 would be to pull the boat back out. Then pull the exhaust riser off and see how clogged the riser and manifold water jackets are. Manifolds and risers are not lifetime items, and they do not last the life of the Engine. They all will eventually rust up and clog up. In saltwater this can be anywhere from 2 to 5 years depending on how often the engine gets flushed. In freshwater they last roughly 12 to 15 years before they rust up. If the manifold and riser are clean. The next place to go is the water pocket grommet inside of the sterndrive. Again when these fail air will get sucked into the water stream, and the engine block will get air bound. If that ends up looking good or still no change, then you would check the circulation pump and see if the steel impeller on the circulation pump fell off. (this isn't common at all, it only happens once in a blue moon, which is why it's the last thing to check). Does that all make sense. I do want to make sure you are happy with my service before you go. If you had a further question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

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Thanks in advance, and good luck

Expert:  Jason replied 2 months ago.

Hello, I never heard back from you. How did you make out?