View Full Version : Need help with 4.3L V6 Volvo in runabout

07-12-2013, 08:21 AM
I took my 2004 Regal 1800LSR in for skeg repair about 3 weeks ago. The shop was to: (1) weld on new skeg (2) replace original impeller (3) replace a leaking water circulation pump gasket. Also, the original impeller was completely in-tact when removed. I ran the boat the day after I got it back and it overheated for the 1st time ever. I immediately took it back to the shop. He said I must have sucked up some gunk, so he cleaned it out and gave it back to me the next day. Again, I ran the boat and it overheated.

Fed up with Shop "A", I decided to take it to Shop “B” b/c I no longer trust the 1st place. Shop "B" has since replaced the thermostat - didn’t fix it. They pulled the lower end off and inspected the hoses near the intake to ensure they’re connected correctly – didn’t fix anything. They pulled the impeller shop “A” installed and put in a “more robust” impeller – didn’t fix it.

Today, they will take it back out on the water and run it to get it up to temp and then use a laser temp gun to measure the actual temp of the engine because they’re questioning if the temperature sending unit is bad. They’ve admitted they’re baffled by this overheating condition.

Symptoms: cools OK while idling and at WOT, but nowhere in between. For example, it overheats at planning speed.

Please help me guys! What the heck is wrong with this motor? It was not overheating when I originally took it to Shop “A”.

07-13-2013, 04:56 AM
just a stupid thought,did you take the thermostat out and try it? I've got new ones bad out of the box.if he took the circulation pump off,did he damage it putting it back on?just throwing some things out there. let us know what you find, and good luck!

07-13-2013, 01:37 PM
I would pull the thermostat and put the boat in the water and run it that way to rule the thermostat in or out as a possible problem.

07-15-2013, 10:42 AM
actually the second shop pointed out the mounting bolts on the water circ pump still have the factory paint covering them, so I think shop A tried to pull one over on me. Still no word from the shop - just waiting to get it back still.

07-15-2013, 10:47 AM
Why is it so hard to find a trustworthy mechanic?

07-18-2013, 07:23 AM
Shop put a new thermostat in and that didn't resolve the overheating issue either.

Next, the tech used a laser temp gun to measure the temperature at varrious points of the engine when the gauge and horn indicated it was overheating. When the gauge was reading 225 degrees and the horn was blowing, he was only getting temperature readings of around 170 all around the engine. He didn't find 1 spot where it read hot, yet the gauge indicated an overheating condition. So, he now believes it's a matter of a faulty temp sending sensor. He said there's 3 on the engine and he's going to replace them 1 by 1 until the problem is fixed. This way, he's not replacing the "good" sensors and potentially opening a new can of worms in the process.

What's your $0.02?

07-18-2013, 03:36 PM
it sounds like you found 2 important things.
1. your problem
2. a honest mechanic

07-18-2013, 03:51 PM
A couple of things have me confused:

First, it is entirely possible that one of your temp gauge senders went bad. But for it to have gone bad at the exact time you had your impeller changed seems like more coincidence than I would be willing to accept. I am wondering if mechanic "A" disturbed something.

The second issue is that a temp sender is most likely to be electric. If it failed, I would expect it to always show bad. But you are describing it acting normal whenever you're idling and at wide open throttle and showing a false overheat when the engine is in the middle RPM range. If that is really how it's working, that would be an odd way for a failing temp sender to work. Maybe it was going junk and its operation was unrelated to RPM. That would make more sense.

I do think mechanic "B" is going about this in a reasonable and logical way using the non-contact thermometer. I'll bet you get to the bottom of this if you stick with his methods.

07-19-2013, 07:03 AM
I think you also found out one other thing - a laser temp gun is a good thing to have around. I use mine all the time. They are cheap at Harbor Freight.

07-22-2013, 08:26 AM
A couple of different people have now told me that Volvo motors MUST have Volvo brand impellers. I told this to 'mechanic B' a couple of weeks ago, but we just wrote it off as a wives tale. Now that so many other things have been ruled out, I brought this question up again to the mechanic. So far, it's had a Cierra impeller installed by 'mechanic A' and then a Johnson Pump installed by 'mechanic B'. On Saturday, I drove to Volvo parts dealer and bought the impeller myself and then delivered it to my mechanic's shop. The mechanic called me and confirmed he received it and then proceeded to tell me there actually IS a visual difference between the Volvo impeller and the other 2 we've already tried - the Volvo impeller is slightly taller! He's installing it today and will report back to me ASAP.

07-23-2013, 07:25 AM
We've learned the hard way that the Volvo motors need to go to a Volvo mechanic. I figured since all the blocks are the same that any Merc mechanic could work on the Volvo and vice versa – wrong! Problem is, the Regal dealer is over an hour away from our house. During this whole ordeal, I’ve found a Volvo mechanic at the Cobalt / Chaparral dealer downtown, which is closer thank the Regal guy in Hendersonville. If my current mechanic can’t figure something out quickly, then I’m yanking it and taking it to the Vovlo guy.

So, the Volvo brand impeller improved the condition, but the mechanic says it’s now blowing water out the back of the sea pump. He says the seals are shot in the back of it. He believes it was pulling air in from the back as well as the non-Volvo brand impellers (Sierra and Johnson Pump) ventilating within the sea pump housing. He ordering a new sea pump housing b/c the seals are not a maintenance item, but part of the entire assembly. The part alone is $400 and should be installed by Thursday and sea trialed once again. If this isn’t the fix, I’m going to the Volvo mechanic.

This is driving me nuts. My wife is pi$$ed that we’ve been without the runabout for a month now and we just keep throwing more money at it. I reminded her this is why I wanted to buy a new / er boat instead of a 9 year old boat. Oh well. Buying used, I saved around $20K, so I guess it’s worth it.

Frantically Relaxing
07-23-2013, 08:10 PM
Endurance-- you've never fixed or worked on something only to have something else go bad immediately after? Geez, I LIVE by that "rule"! Like, the fuel pump problem I'm having with my generator- that problem originated when testing my AC unit that kept tripping the breaker! I fired the genny to see if the AC would still trip (to tell me if my shore power was the culprit)-- Well, the breaker tripped! Great, pretty sure the AC is the problem, not my power supply... So I reset the breaker after a minute to do a second test for good measure, and 10 seconds after firing up the AC, the whole boat shut down! At first I thought I'd REALLY fried something! Instead, for the first time in the 7 years we've owned the boat the genny up and quit, because it "ran out of gas" -even tho there was still 60 gallons of gas in the tank! --and just as I'd finished troubleshooting ONE problem-- I got lots of examples, but I digress... ;)

THAT all said-- check around to see if one of the sending unit wires (or any other wire) was accidentally caught and tightened down under say, the edge of the water pump or some other bolt-- I've had that happen too! Sensors work by resistance to ground, and a full-on ground usually means a full-on gauge reading--

<edit> since I didn't see your last post until after I posted the above-- :)

Has any of these mechanics checked to see if the engine pump's impeller is actually turning? I've heard of more than one pump that for whatever reason became un-attached to the pump shaft. or was so corroded it couldn't pump-- It almost sounds as if the sea water pump is trying to do all the work, which, it might be able to do well enough at idle and WOT--? And without the help of the engine pump to move the water thru the risers, the back-pressure on the sea water pump may cause water to seep thru the seals as it's supposedly doing...

This is all just conjecture, but sounds plausible to me, at least.. Who knows, maybe the mechanic left a shop rag in with the engine pump when he buttoned it up. Doctors do it... !!

07-24-2013, 06:28 AM
Frantic - you're scaring me. I'm clicking my heels together as I type chanting "replacing the sea water pump is the fix!"

07-29-2013, 08:19 AM
1 "boat buck" and 1 month later, IT'S FINALLY FIXED!!!! In the end, the sea water pump seals were shot. A steady stream of water was pouring out the weep hole onto the rotating belt pulley. The pulley was slinging the water around the engine compartment like a damn sprinkler head water the lawn. This was not the main issue, but a contributing factor.

The main issue: when the lower unit was removed to weld on the new skeg, a stainless steel or brass tube that carries the water from the lower unit to the upper unit slipped from its seating on the upper part of the lower unit. When you drop the lower unit, this tube stays on the upper unit. When it was put back together, it was not properly seated back into the upper housing or lower housing correctly. When running at low RPMs, it would get just enough water to cool the engine, however at higher RPMs, the upper part of the drive comes out of the water allowing it to suck air instead of water. The 1st shop missed this and the 2nd shop missed this the 1st time they dropped the lower unit. The second time he dropped the lower unit, he found this and the problem was fixed immediately after.

My lesson learned from this whole ordeal is that my Volvo engine and outdrive are going to a certified Volvo tech from now on! On the flip side, my boat should never overheat on me again b/c we've replaced nearly all the cooling side of the engine!

I hope this thread helps some other poor soul with their overheating problems in the future.