Help Test OIL/Water Gauges, overheat alarm.

[lmannyr]

There is ONE sensor on the thermostat housing. I put it to ground and got a flicker on the volt meter and nothing else.

There is ONE sensor on the WATER PUMP. I ground it, and got nothing on any gauges.

No sounds in ether case.

There is no sound when turning engine on. I've read that the alarm should sound momentarily on startup.



Where do I start?

 

[lmannyr]

Re: Help Test OIL/Water Gauges, overheat alarm.

UPDATE:

Thermostat sensor when grounded does fully deflect the temp gauge needle.

What is the sensor on the water pump?

Why doesn't the buzzer go off when the temp needle get a full deflection?

Bought a 12 v buzzer from radio shack and still nothing.

 

[Bt Doctur]

Re: Help Test OIL/Water Gauges, overheat alarm.

If your equipped with the system , the tan/blue wire goes to the alarm. It joins the hi-temp,low/no engine oil, outdrive oil together. This link might help.
http://www.boatfix.com/merc/Techbk/96/96HGD4.PDF

 

[Don S]

Re: Help Test OIL/Water Gauges, overheat alarm.

The gauges have different senders than the alarm. Alarms have on/off switches while gauges use variable resistor type senders.
PS, the 96 tech manual won't give you the wiring diagrams of your 89, might want to hit the Adults only sticky at the top of the forum for the full manuals for your engine and drive.

 

[lmannyr]

Re: Help Test OIL/Water Gauges, overheat alarm.

The old buzzer has a capacitor looking thing wired inline. I disconnected the tan/blue wire from the buzzer and grounded it, nothing. I put the the radio shack buzzer in place of the old one and still nothing when grounding the tan/blue wire. There is a purple wire (ign?), tan/blue, and one more.

Back at the engine, there are 2 sensors, one on the thermostat (verified its a sender) with 8v tan wire (not tan/blue), and the other on the water pump (assuming switch) with 12v green wire.

edited...

 

[lmannyr]

Re: Help Test OIL/Water Gauges, overheat alarm.

I thought these sensors are grounds only.. Why does the sender, and whatever is on the water pump (guessing water switch for buzzer) sensor is have 8 and 12 v respectively?

 

[rodbolt]

Re: Help Test OIL/Water Gauges, overheat alarm.

remember, one is a SWITCH the other a SENSOR.
sounds like someone has been cobbling your sweeties wiring system.
for many years tan was temp send and tan blue was temp switch on or off.
most sender circuits work on a 5V system while quite a few switched setups use 12V.
the sensor typically is a thermistor device that resistance will vary inversly to temperature.
the switch is simply on or off.
most sensors for temp decrease resistance when temp increases to allow more current flow which will increase the magnetic field in the needle movement windings and cause the needle to pull towards the hot range.
some work opposite especially outside the US market.
what your going to have to do is simply trace the circuit between the switch and the horn and then the horn to the 12V supply from the ign circuits.
the temp sensor has NOTHING to do with the alarm horn on that model hull wiring.
sometimes them radioshack buzzers just wont work on marine systems.
careful what you assume, especially if backyardigans have ever been involved.

 

[Don S]

Re: Help Test OIL/Water Gauges, overheat alarm.

careful what you assume, especially if backyardigans have ever been involved.

backyardigans I like that word, and it is NOT the same as a DIYer that knows what he is doing, has a manual, and understands what is going on.

 

[rodbolt]

Re: Help Test OIL/Water Gauges, overheat alarm.

we have been plauged in our area with several mobile backyadigans in the past few years.
it gets interesting working behind them.
with volvo,mercruiser and EFI yamahas.
its the best word I could come up with.
a do it yourselfer with the correct manual,a clue and the ability to heed advice is a decent customer.

 

[Bondo]

Re: Help Test OIL/Water Gauges, overheat alarm.

Quote:
careful what you assume, especially if backyardigans have ever been involved.
--------------------------------------------------------------------------------

backyardigans I like that word, and it is NOT the same as a DIYer that knows what he is doing, has a manual, and understands what is going on.

Ayuh,... And this guy's barge has most definitely been Backyardiganed

It sounds like Little or Nothing is Original....

Purcahsed 1989 220 Sundancer Merc 5.7L (holly carb, power marine intake), SEI 106 (Alpha 1 Gen I).

 

[lmannyr]

Re: Help Test OIL/Water Gauges, overheat alarm.

For safety sake, it's a Marine Holy carb (USCG Approved). I'm a "Let's Keep it original/factory" type of guy. Can't help it when when you buy a used boat that things are "Backyardiganed". At the time of purchase, my boat knowledge was "if it looked and ran good then it was good."

Since I've bought this boat, I've fixed/updated/maintained it by the Mercruiser manuals posted in the Adults Only section. There have been times when the boat was offline for months due to minor things because it's "JUST NOT RIGHT." Safety is my #1 PRIORITY. Hence, fixing the alarms I didn't know it had. Every day I learn something new thankfully to this and other sites.

So......

I can I make sure the sensor on the thermostat is in fact a switch?

Found a sensor on the port side of the distributor with 2 wires coming off of it (red and purple). The colors don't match the standard boat wire colors.

Since the engine was rebuilt in 2000 by god only knows who, my best guess is this is the oil pressure sender, i'll verify that in a min.

 

[Bondo]

Re: Help Test OIL/Water Gauges, overheat alarm.

I can I make sure the sensor on the thermostat is in fact a switch?

Ayuh,... A Switch is a Make, or Break, to ground...
A Sensor is a Variable Resistence to ground....

My previous point is that Mercruiser has Never, Ever used a Holley carb on a SBC motor....
Hence,... Stock means Nothing... God only knows what else ain't OEM...

 

[lmannyr]

Re: Help Test OIL/Water Gauges, overheat alarm.

Ok so the sensor on the port side of the distributor has 10v on purple wire and the red wire is ground. When purple and red are put together, the fuel pump turns on.

So what sensor is it?

 

[Bondo]

Re: Help Test OIL/Water Gauges, overheat alarm.

So what sensor is it?

Ayuh,.... It's Not....
It's the oil pressure Switch for the electric fuel pump...
The Red is Not ground...

 

[lmannyr]

Re: Help Test OIL/Water Gauges, overheat alarm.

Bond-o, your right, RED has 10v purple is ground/ign

Ok.. So I found the Oil pressure switch. Is there another oil switch for the buzzer? Or do I wire it in to this oil switch for fuel pump?


thanks..

 

[rodbolt]

Re: Help Test OIL/Water Gauges, overheat alarm.

post a pic of the intake manifold.
I am almost sure you have either an indmar long block assy or a marine power long block assy.
these block assy use a carter rotary fuel pump mounted on the lower stbd side of the engine and MUST be wired through a switch from the oil pressure or a dedicated output from the altenator to insure the pumps shuts down for any reason the engine quits.
the above blocks did use a 750 holley and DID not come prewired.
the ign,choke and oil pressure wiring had to be added by the end user installer.
post some pics.
your wireing color indicates the original wire colors have been changed.

 

[Don S]

Re: Help Test OIL/Water Gauges, overheat alarm.

Even more that is not OEM. The 89 engines didn't have an electric fuel pump. Even when Merc did start using electric fuel pumps, they didn't use red wire on oil pressure switch and it wasn't located up next to the distributor.

Now, on to your problem. you may have a buzzer problem, and some Radio Shack buzzers can be polarity sensitve. Are you sure it's right?
It sounds to me like your OEM buzzer is the style with a 15 second time delay built into it. That was so you didn't have to hear the buzzer when you first turned the ignition on when starting.

 

[lmannyr]

Re: Help Test OIL/Water Gauges, overheat alarm.

Don S, remember this engine was rebuilt in 2000. The block number indicates a 2000 block.

This Radio Shack buzzer is in fact polarity specific. I'll try it again. reversed.


The Temp sender is to the left of the thermostat housing on the intake manifold. The switch ( I believe is the switch) is just below on the the water pump.

 

[Bondo]

Re: Help Test OIL/Water Gauges, overheat alarm.

The switch ( I believe is the switch) is just below on the the water pump.

Ayuh,... Considering that, That is the coldest water in the motor,...
I can see Why that switch ain't gonna work...
It needs to be in the Intake manifold, or the Hot side of the T-Stat housing...

That port is Only used for cold water return from a heating appliance...

 

[rodbolt]

Re: Help Test OIL/Water Gauges, overheat alarm.

thats why I was hoping for a picture.
the Barr,indmar and PCM motors use a funny looking AL intake and come with the intake and carb installed, the EST distributer installed with plug wires and plugs and the carter rotary fuel pump installed but NOTHING is wired and no manifolds or accessory brackets.
some of the intakes had NO provision for any senders or switches so one of the two had to be either teed or relocated to the circulating water pump.
one of the places I work for sells a lot of these so called universal fit 320HP 5.7 carbed base engine assymblys that are universally garuanteed not to fit a dang thing without a lot of modifications to various brackets and such as well as chopping the engine harness.
but most of the above engines had an oil pressure switch that would OPEN when oil pressure dropped OPENING the fuel pump circuit.
typically wired with a wire from the starter R terminal to the pump side of the switch and the purple ign wire on the other terminal allowing the pump to run when cranking and shut down with loss of oil pressure.
these wires MUST be ADDED by the installer.
some installers actually make diagrams to give to the end user and can actually make a neat package, others have issues.