1994 Volvo Penta 3.0 GL overheating (long read)

[JesseRuiz]

Hi all,
I have a Volvo Penta 3.0GLMMDA in my 1994 Glastron 175 ssv with an SX outdrive and I'm having overheating issues that I've been working through. It's already ruined 2 of my trips to the water and since I can only get my engine to overheat when I put a load on it and I live 1.5 hours away from the river its been tough. I had the engine completely rebuilt at the start of last season and had no problems all of last season.

Since my first trip this season I've had trouble. Memorial day weekend boat started to overheat within 15 minutes, I had my eye on it, shut it down at 225, let her cool and limped to the beach.

Here is what I did that weekend on the water:

• Checked impeller(looked good, replaced anyway with new gasket)
• Checked hoses all clear of obstruction
• Pulled hose off of end of thermostat had plenty of flow
• Test run (overheated)
• Pulled thermostat saw it was stuck at an angle (removed thought that might be it)
• Boat still overheated after a 15 minutes shut it down and trailered her for the remainder of the trip.

Got home and had my local mechanic go though it.

• He went through hoses (all clear)
• Checked impeller (brand new)
• Checked compression (good)
• Checked oil (good, good level, no water)
• Checked riser (found some metal debri resticting water and cleared it out)
• Mechaninc ran on muffs, plenty of flow and thought that was it.

I was happy got the boat already for another weekend adventure. The night before I hooked the boat up to muffs (idle only) and I noticed that the boat was idling at 175 degrees which seemed hotter then usual and now my oil pressure was a little low, but trip was already set so I went for it.

15 minutes into my trip my boat overheated. Cut it off, let it cool and found that I could drive around at low rpms without overheating. It only overheats at full throttle but then of course my oil pressure dropped to 0 and that was it for my trip since I didnt want to damage anything.

Got home and this is what I did:

• I checked the oil pressure with a manual tester and presssure was good, ordered a new sender.
• Ordered a new temp sender just in case.
• Installed new oil sender (Fixed, bingo!)
• Installed new temp sender (Still idles a lil warm)

I really dont want to waste another trip and I feel as if I havent solved the overheating issue.

This is what I'm planning to do:
I read on this forum that maybe a flapper could have burnt up and partially clogged my the exhaust which would only cause overheating when the flow is restricting. Makes sense so I've ordered new gaskets and I'm going to pull the riser myself this weekend and check to see if the flapper is the culprit.

Here are some temperature readings I took with a laser reader while idling for 15 minutes on muffs:

I live in the desert so it was 100 degrees ouside while I was performing these readings.

I was hoping the exhaust manifold would show it to be alot hotter which would have made me think restriction there but it was just 15 degrees hotter. It's weird that nothing read 185 but Im guessing that the internal water is hotter than the external metal or rubber.

Im not a mechanic and I'm new to engine work but I'm digging in for this one, so if anyone has some sugestions, ideas or thinks I'm going in the wrong direction please let me know I'm all ears.

Thanks,
Jesse

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Your temp readings indicate that your gauge may be off. Let the engine run longer to get more stable and take again. Take the temp righ tat the temp sender too.

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Your temp readings indicate that your gauge may be off. Let the engine run longer to get more stable and take again. Take the temp righ tat the temp sender too.

Yeah the engine had been running for about 15 minutes. I did take a reading of the temperature sensor and it said 145. I just thought that maybe the temp sensor was hotter on the inside.

Hmm now I'm trying to rembember what the gauge said before I even started the engine. I'll have to look at that later, I wanna say before I started the engine it was already at 100 degrees, but I just assumed that was because it gets hot where I live and the boat is outside in 115 degree weather. I'll double check those numbers and run it on idle for longer.

Thanks for your feedback!

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

The temp should eventually get to a steady state value but it may be longer the 15 minutes. If you want, unscrew your temp sensor and put it into a pan of boiling water and constantly measure the temp of the water and what it indicates on your gauge as the water cools. That is the ultimate test.

If the temp on your gauge reads higher than 212? when you have the sender sitting in boiling water, you know you have a gauge problem.

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Here's an update...
Just turning the key to the on position without starting the motor the temperature gauge reads 125 degrees. I checked the temperature of the sensor in the engine and it was 95 degrees.

I then put the sender into a cup of hot water and the gauge said 165, the water temperature was actually 140.

In an attempt to troubleshoot the gauge, I went down to Pep Boys this morning and just grabbed a temperature gauge unwired the one on my dash and wired the new gauge in and the temperature was about 150 degrees when the block was still 95 degrees, so that didn't work at all. I haven't started my boat since I know the temperature is still going to be off.

Jesse

 

[Nebfarmer]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Get an infared thermometer or heat gun as they are commonly called and take a few readings of the block and both sides of the thermostat. Block temp and coolant temp should be nearly equal. Also most temp gauges have to be matched to the sender so your Pep boys gauge is probably not accurate. Bad grounds can also cause high readings. Are your other gauges working right?

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Thanks for the info,
I do have an infrared thermometer I picked up at Harbor Freight and that's what I've been using. If you see my first post I linked a photo with various readings.

All my other gauges are working fine except for my trim gauge which has never worked.

I did test the sender and it pegs the max temp when I ground it out. By turning the key to the on position I would expect the gauge to read what the temp is. Without even starting the boat the temp reads 125 degrees which is about 30 degrees hotter than it should read. I can get a new Faria gauge for about $30 I wonder if that will solve the problem.

I first thought the boat was overheating because of an obstruction in the exhaust riser but now I’m thinking it’s more electrical. So before I start pulling things apart I would like to get an actual good temperature reading.

Is there something else I should do to test the gauge? I do have a multimeter handy but I’m not sure how to go about testing the gauge.

Thanks,
Jesse

 

[billbayliner]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Where the raw water hose connects to the outdrive there is a hose connection. Pull the line off and remove the hose connector.

Check it for holes and see if there is any pitting in the flange portion of the suspension forks that may, when higher speeds are achieved and that section of the drive is no longer submerged, allow for air to enter thus not enabling the raw water pump to draw.

Hose connection 854031

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Is there something else I should do to test the gauge? I do have a multimeter handy but I’m not sure how to go about testing the gauge.

I would test the sender first. Somewhere in the manual there must be a chart that indicates what the resistance is for various temps. My manual is a few years newer than your engine but it must be the same.

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Check it for holes and see if there is any pitting in the flange portion of the suspension forks that may, when higher speeds are achieved and that section of the drive is no longer submerged, allow for air to enter thus not enabling the raw water pump to draw.

Bill, you realize this is an SX drive right?

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

I found a document on the Faria site that says the water temperature resistance should be like the following:
100? - 450 ohms
175? - 99 ohms
250? - 29.6 ohms
http://faria-instruments.com/site_manuals/IS0085E.pdf

I'm not sure though how to test with a multimeter because there are 3 posts on the back of the temperature gauge.

I'm also going to buy a peice of clear tubing to run from the hose that comes from the raw water pump to the thermostat to check for air bubbles. I dont know how this would effect the temperature being off but it's worth checking that atleast there is no air in the cooling system.

Thanks,
Jesse

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

I'm not sure though how to test with a multimeter because there are 3 posts on the back of the temperature gauge.

Measure at the sender. Remove the wire that goes to the sender before you take your measurements.

Buy a couple resistors or get a pot and set it to those same resistances and hook it between the wire that goes to the gauge and ground to test the gauge. Again, the wire should not be connected to the sender and you adjust the pot before connecting it.

http://www.radioshack.com/product/index.jsp?productId=2062300&locale=en_US

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Measure at the sender. Remove the wire that goes to the sender before you take your measurements.

Buy a couple resistors or get a pot and set it to those same resistances and hook it between the wire that goes to the gauge and ground to test the gauge. Again, the wire should not be connected to the sender and you adjust the pot before connecting it.

1K-Ohm Horizontal-Style Trimmer - RadioShack.com

Thanks for all your help with this Bruce, I really appreciate it. I dont totally understand though, so up front at the gauge I disconnect the one wire going to the sender, which is probabbly the middle one? Then I wire the resitor to that middle post and ground it to test. How do I know how much to turn the screw on the resistor, so I know Im adding the right resistance, am I using the multimeter somewhere in there to see the resistance reading?

Thanks,
Jesse

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

I would leave the wires at the gauge alone and do all tests back at the engine.

There will be 3 terminals on the potentiometer. You measure between the wiper terminal and one of the other terminals. Adjust until you get the desired resistance measured with your meter. Make sure you do this measurement without the pot connected to anything. Using the same terminals on the pot, connect between the wire originally connected to your sensor and to ground(use a jumper wire).

I would actually first start measuring the sender's resistance at various temperatures. I think your problem is more likely there and its the easiest test to do first. Again, you have to remove the wire when taking your measurements.

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Oh I get it, thanks! I picked up the potentiometer you reccomended during my lunch break. I'll give it a shot this evening and let you know my results.

Thanks,
Jesse

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

1K Ω right?

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

1K Ω right?

Yes 1k-ohm
micro-size potentiometer
50vdc 0.1 watts

It did not work out as expected. I hooked up my multi-meter and when I would turn the screw the numbers would just fluctuate. I set it at the 2000 ohm mark because that was giving me more numbers then the 200 ohm mark.
Here's the multi-meter that I have.


After a half hour of turning it off and on and turning the screw I gave up and took it outside to the boat.

I disconnected the sender and wired the potentiometer in. I then turned the screw till I got the correct temperature on the gauge. Once I dialed in the correct temperature in I would take the alligator clips to the multi-meter. Back to my meter problem, the numbers would start fluctuating and they would continue to grow or decrease over time. Must be the meter because when I would turn the screw and dial a temp in that would sit steady with no fluctuation.

Here are the readings I got.
100? - 004 with 2000 selected on meter
175? - 008 with 2000 selected on meter
250? - 001 with 2000 selected on meter (couldn't get a good reading number was sometimes at 015)

I also noticed that 175? -250? - to gauge pinned was supper touchy it was like turn the screw driver a hair it was passed 250?, turn it back a hair it was at 175?, tap it forward a touch it was 200?

Very frustrating. Sorry this may not help much.

Thanks,
Jesse

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

When you adjust the pot to get 100?, you then need to disconnect the pot from the circuit and then measure it. You can't measure it while it is in the circuit. If you don't remove it, it measures the circuitry in the gauge too and you don't want that.

You may have to get a different pot if that one was too touchy.

Or just buy a few resistors. 450, 100 and 30 would be perfect to do the 3 temps. 30 might be tough to find, 3 100s in parallel will give you 33. 470 is more common than the 450 but close enough.

Now measure the resistance of the sender without its wire attached at different temperatures. That was a more important test anyway.

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

So I just read your first post again and you said you bought a new temp sender. Is that the one that is installed right now? Just for comparison sake measure the resistance of both the new one installed in the block and the old one to make sure they are approx the same resistance at the same temperature.

I would also make sure all the connection at the water temp gauge are on tight. If you had a bad ground, all bets are off on the gauge reading correctly.

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Yeah that's what I did. Once I got the correct temperature I would disconnect it and take to the meter. I guess its supposed to be touchy at the high degrees looking at the chart there's only 70 ohms seperating 175 degrees to 250 degrees.