1982 Perkins 4108 temperature sensor location

[SSgtPitt]

There was another thread reagrding this, a guy spent days tracing the wrong wires then found the right ones, I can’t find it now.
My coolant temp gauge quit and I’m leaving for the Bahamas in a week n a half.
The sensor on the front top of the engine right next to the t-stat has one terminal with a wire lead that goes to the oil filter. I get nothing on the ohm meter even after reaching 147 degrees.
Is this a high temp alarm or my coolant temp gauge?
Thanks for the help.

[SSgtPitt]

Sorry for the wrong direction pics. iPhone shows em just fine.

[NoTies]

If the wire heads off to the oil pressure switch it is probably safe to assume it is the warning light/buzzer switch and not the gauge sender.

[coopec43]

Is this any help?

QUOTE:
Hi Tim:
We completed installation of the engine instruments on Paragon this weekend. Work included new senders, new engine wiring harness, new instruments and panel. Shelton Sawyer who owns Ostara, a M382 sister ship on Lake Lanier helped. We had done the same work on his boat a few weekends earlier. The shared project worked well - provided motivation to get the work done, help, shared tools and resources, etc.
In the process of doing this work I also replaced the starter, installed a new cockpit branch electrical panel to replace the three switches, and assorted other things. I will write in more detail about the process and illustrate it with photos.
First, I will try to answer some of your questions.
- I purchased the instruments, senders, panel, and wiring harness from TransAtlantic Diesel so they were matched and designed for use on a Perkins 4-108.
- The oil pressure sender does not have a brand or model on it. The box was labeled as "SD0003", the sender is stamped 80 psi
- The oil pressure switch is a Cole Hersee "8610"
- the water temperature switch is in a box labelled ISSPRO "R363E", it closes at 200 F, and is 3/8" pipe.
- the water temperature sender was by the same manufacturer but I don't have the model number. Ask TAD. It was also 3/8" pipe so I used an adapter bushing to fit the 1/2" hole on the block.
- I have attached photos of the oil pressure switch and sender - they are on the port side of the engine. I took these when I had the engine out of the boat. (Why I didn't replace them at that time is a good question.) The switch is in front. I removed the starter which made accessing the sender and switch much easier. On Shelton's boat we did it with the starter in place - tough but do-able.
- I have attached a photo of the water temperature switch and sender on the top front of my engine. Sender is threaded into block. Shelton's engine is older with the tank across front. The sender was in the front, the switch was in the back in the top of the head - we could not get it out and re-used it.
- There was no audible alarm on the original panel - there were two warning lights - the one on the port side was for oil pressure, the stbd for water temp. Neither worked on my boat nor did the oil pressure gauge. After the temperature gauge needle broke, it was time for action.

Let me know if you have questions.



Oil Senders - Perkins 4-108



Oil Pressure Switch - Perkins 4-108



Oil Pressure Sender - Perkins 4-108



Water Temperature Senders - Perkins 4-108


http://www.morgan38.org/morgan38/ind...l-plate.10980/

[Wotname]

Originally Posted by NoTies

If the wire heads off to the oil pressure switch it is probably safe to assume it is the warning light/buzzer switch and not the gauge sender.

Yes and a reasonably quick way to check is to remove it and heat it water. If a switch, continuity will usually occur somewhere between 80 and 100 C.

[DougR]

Because the temp function and the oil function are wired in parallel, it's reasonable to assume they are both alarm switches for over heat and low oil pressure. Neither should show continuity to ground unless there is low oil pressure ( maybe below 8 or 10 lbs) or high temp over perhaps 205F. If either one closes to ground the alarm function will activate.

DougR

[Warby12]

Our temp sender is at the back end of the engine, on the head behind injector for cylinder 4.

Temperature sender right? that sends the temperature, different to a temperature switch which sets off an alarm, wired with the oil pressure switch as said above.

[Warby12]

To add to that, the one at the front / top of the engine connected to the oil pressure switch down on the side, on our engine, is the temp 'alarm'. The photo i posted is of the sender (or sensor) on the back / top of the engine. We have both and these engines do vary, but anything stuck into the head, with wires coming off it, is gonna be temp measuring of some kind.

Check for broken connection between sender and the earth or sender and the gauge.

If the wires are ok, then it's either the sender or the gauge

[SSgtPitt]

Originally Posted by Warby12

To add to that, the one at the front / top of the engine connected to the oil pressure switch down on the side, on our engine, is the temp 'alarm'. The photo i posted is of the sender (or sensor) on the back / top of the engine. We have both and these engines do vary, but anything stuck into the head, with wires coming off it, is gonna be temp measuring of some kind.

Check for broken connection between sender and the earth or sender and the gauge.

If the wires are ok, then it's either the sender or the gauge

I love this Forum.....Dead on Warby.

Shortly after I posted I started tracing the wires backward with my Fluke. The gauges are behind a couple of custom wood panels that are a pain to remove.



I traced the wires and found where it was broken. Probably from me replacing the throttle and shifter cables or the heat exchanger.



I also found the coolant sensor right behind injector #4, it's not very big.



For all you "shade tree" Sparkies. If you don't have a Fluke, they're awesome. This one has helped me find buried wires in numerous homes and has been fantastic in sorting wires behind the bulkheads and headliner.

[Warby12]

Well done we recently rewired the engine and replaced gauges and senders, so it's very fresh in my mind.

Fluke sounds good!

[thereefgeek]

Very helpful tracing out electrical problems when all the wires are painted "Perkins Blue"...

[Kystgeita]

Hello,
We are currently retracing old cables in my Trintella 3A, with a Perkins 4108 Diesel engine.
The last owner cut most of the cables for some reason, so it’s a bit of a guessing, and testing game.

Do any of you recognize these sensors, and can tell me what they are?
And, what is the last sensor alarm light on this original Perkins panel, with the P in the symbol?

[DougR]

The sender on the cylinder head next to the thermostat housing is usually the freshwater temperature sender, and it drives the temperature gauge. If there is no temperature gauge it could be a switch for the temp alarm, as shown on your alarm panel, center light.

The “sender” mounted near the air inlet/ air filter is not a sender at all, but it is a solenoid fuel valve for the cold start device.

Don’t know what the third light on the alarm panel is, but it looks like a raw water pump flow alarm, and you might find a switch for that in the exhaust mixing elbow.

[Wotname]

Originally Posted by DougR

............

Don’t know what the third light on the alarm panel is, but it looks like a raw water pump flow alarm, and you might find a switch for that in the exhaust mixing elbow.

My guess it is a raw water exhaust temperature alarm given the designator '*C' to the left of the impeller looking symbol.