88 Mercruiser 3.0l

[jwp101]

Can someone help me locate the Temp sending unit and Oil pressure sending units on a 88 Mercruiser 3.0l. I would like to replace them. What should these both read in idle. I am not sure if even need to replace. The temps runs at about 120 and the oil is around 40. Please help. I am a newbie but not afraid to do my own work.

 

[Bondo]

Re: 88 Mercruiser 3.0l

Can someone help me locate the Temp sending unit and Oil pressure sending units on a 88 Mercruiser 3.0l. I would like to replace them. What should these both read in idle. I am not sure if even need to replace. The temps runs at about 120 and the oil is around 40. Please help. I am a newbie but not afraid to do my own work.

Ayuh,... Welcome Aboard,... I don't see anything wrong,....

Is that temp on the muffs, or in the pond,..??
Ditto the oil pressure,..??

The Temp Sender is usually in the T-stat housing...
The oil pressure sendin' unit is right next to the distributer I believe on yer motor...

 

[jwp101]

Re: 88 Mercruiser 3.0l

That is with the muffs for both readings.

Here is why I asked. I was out on the water (fresh) last weekend and thought I ran out of gas. The fuel sending unit was bad so I had no guage to let me know. When I knocked on the tank it sounded empty. I repalced the sending unit and found that I had almost 3/4 of a tank of Fuel. Know that I have fixted the fuel sending unit, fuel filter,. I want to make sure the other gauges work. I tried to find a photo of the engine so I could verfiy locations but came up short. I will look once in fron tof the boat.

The readings seemed fine for running on Muffs? what should they be at say 3000 rpms?

 

[jwp101]

Re: 88 Mercruiser 3.0l

I went out on the boat yesterday. The sending unit worked great we burned off 3/4 tank (20g is full) 3000-4500 rpm for about 2hrs as we where heading in I noticed I lost power and can could not past 2500 rpm's. The temp read 140 and oil pressure was 40-45. the motor salled. I waited about 5 min and it than ran normal. Any idea's bad t-stat??

 

[Rocky_Road]

Re: 88 Mercruiser 3.0l

I went out on the boat yesterday. The sending unit worked great we burned off 3/4 tank (20g is full) 3000-4500 rpm for about 2hrs as we where heading in I noticed I lost power and can could not past 2500 rpm's. The temp read 140 and oil pressure was 40-45. the motor salled. I waited about 5 min and it than ran normal. Any idea's bad t-stat??

Your thermostat would not cause this. How old is your gas?

You may have some crud in your fuel tank that made it onto your pickup tube screen...restricted your fuel flow...and dropped off when the engine stopped. Sounds wierd, but I have seen it happen.

P.S. Your engine most likely came with a 160 degree thermostat originally, which means that your 140 reading seems low. You can test your gauge by grounding the temp sending unit wire to the engine with the key in the "RUN" position. A good gauge will peg full HOT (all the way to the right).

Happy boating!

 

[jwp101]

Re: 88 Mercruiser 3.0l

Thanks for your reply.The gas is the remaing from when I stored ot last season. Wouldn't bad gas cause it to run bad all the time not just at or above 3000rpm? i will check the gauge tonight. If they gauge read ok should I go ahead and change the temp sending unit and or the t-stat? I appriacte all the help.

 

[Rocky_Road]

Re: 88 Mercruiser 3.0l

Thanks for your reply.The gas is the remaing from when I stored ot last season. Wouldn't bad gas cause it to run bad all the time not just at or above 3000rpm? i will check the gauge tonight. If they gauge read ok should I go ahead and change the temp sending unit and or the t-stat? I appriacte all the help.

Ethanol is a pretty good solvent, and can be the cause of additional 'crud' in your tank. The gas itself could still burn, but the crud can end up restricting your gas flow. Like I mentioned, I have witnessed this crud being sucked onto the tank pickup screen, and then falling off when the engine stalls or is turned off. Then the engine runs fine...until the screen gets stopped again.

If this were mine...and the gauge tested OK...I would look at the thermostat next. Temp sending units are pretty simple, and don't go bad that often.

Happy boating!

 

[jwp101]

Re: 88 Mercruiser 3.0l

Thanks Rocky!! I will test gauge to be sure. I have removed all the gass from the tank and will start new.

On a differnent note that I did not mention. When I have the engine cover off and go from neutral into gear I hear what sounds like a chain rattilng once in gear it is gone. Timing chain?? I hope not..

This site is great...

 

[Rocky_Road]

Re: 88 Mercruiser 3.0l

Thanks Rocky!! I will test gauge to be sure. I have removed all the gass from the tank and will start new.

On a differnent note that I did not mention. When I have the engine cover off and go from neutral into gear I hear what sounds like a chain rattilng once in gear it is gone. Timing chain?? I hope not..

This site is great...

Let your heart not be troubled!

There isn't any real clutch to make your gear changing nice and quiet...you are hearing the gears find each other, and mesh. Most of us do the gear changing swiftly, to make the obvious less obvious. I would rather have my gears 'clunk' into position, then go slow and have the ends of the gear teeth fighting all of the way!

Happy boating!

 

[jwp101]

Re: 88 Mercruiser 3.0l

Great!!! Thanks for all your Help...