Intermittent overheating after new t-stat/impeller

[Kingfam3]

Greetings again ladies and gents! So it's a new season, and a new set of wonderful boating problems. Getting right to it, my 2001 VP 3.0GSP-A W/SX-M outdrive is overheating yet again...last year I had similar problem thanks in large part to a very old impeller that essentially crumbled and proceeded to lodge itself in every orafice it could find. a few random overheats later and a frequent cleaning out of my circ pump and hoses removed all of the pieces, and then again this year I am getting it again! The boat had a new engine coupler installed at the end of the season before it was winterized and when picking it up this year up at Raystown, I took it out there and ran up and down for an hour and a half with absolutely ZERO problems, temp never hit 180. 3 weeks later(yesterday) we take the family to the river and it idled fine for 5 minutes, then as soon as we got away from the dock I watched the need hit 180 and continue to rapidly climb as the alarm started going off. Instantly shut it down and began checking hoses, water in from outdrive is nice and cold, water out of sea pump to t-stat is warmer, water from t-stat to circ pump is HOT, and so is the hose from other side of t-stat to the manifold.

Today I took everything apart, did the boil test on T-stat and it opened just fine, the impeller that was replaced just last year also looks perfect...was thinking might be further down the line, but why would t-stat housing and everything around it be so hot unless the thermostat is just picking and choosing when it wants to work? (like the 1st time out at Raystown, and during the boil test, but yesterday it just felt like overheating)

Any ideas? I've attached pics of impeller and t-stat (forgive the pink towel the parts are placed on, we work with what we've got). Thank you in advance for your assistance. Historically you have all been so helpful.




V/R,
Ted King

 

[johnmorgan]

Re: Intermittent overheating after new t-stat/impeller

not to be rude but was the thermostat facing the right way

 

[Kingfam3]

Re: Intermittent overheating after new t-stat/impeller

Yes it was. New thermostat installed middle of last season before the engine coupler broke and I had bigger problems. Like I originally stated, no overheats last month when we took it out for the first go of the season either, just wasn't happy yesterday.

 

[Don S]

Re: Intermittent overheating after new t-stat/impeller

Raw water cooled thermostats tend to stick at times as they get older. Might be time to replace it with a new one.

 

[Kingfam3]

Re: Intermittent overheating after new t-stat/impeller

That's what I was thinking as well as far as the intermittent part of it...maybe when I was removing it from the housing I "unstuck" it for the boiling water test and that's why it tested fine...The other thing was, I don't know how a marine thermostat degrades, but for that one supposedly being new last year and only being in the water a handful of times, doesn't look like a 1 yr old T-stat? Bottom line, I'm never having anyone do minor repairs like that again...I have a SELOC, I can figure it out myself...too many people out there willing to take your money and tell you it's fixed when they didn't do the work they said they did. Thanks for all your help so far! I'm ordering the gaskets and a new t-stat tonight. I'll let you know how I make out.

 

[Kingfam3]

To replace, or not to replace circulator pump

To replace, or not to replace circulator pump

VP 3.0GSP-A/SX-M

As you may remember in my post yesterday I am troubleshooting an intermittent overheating issue...please look at the attached photos and let me know your opinion on whether I should just replace the old circ pump while i'm at it, or get some new gaskets, hook everything up again, run the boat without the T-stat and see whether or not it overheats to rule out the thermostat(i've already bought a new t-stat anyway to put in, but am going to try the no-thermostat test to see if I get the same result). Also, the volvo schematic calls for part # 3858340...the sierra part that replaces 3854017 claims it works on ALL 3.0 inline 4 cylinders...Besides saving $140, why would i not just get the Sierra replacement?

 

[Kingfam3]

Re: To replace, or not to replace circulator pump

Re: To replace, or not to replace circulator pump

Also, all of the bearings etc. turn fine...no mechanical defects or clogged passages.

 

[Don S]

Re: To replace, or not to replace circulator pump

Re: To replace, or not to replace circulator pump

If the impeller is tight on the shaft, and it doesn't leak and turns smoothly, there is nothing wrong with the pump. Why don't you just fix the thermostat first and see if that fixed the problem instead of taking everything apart for no reason.
You also need to keep all of this under one thread instead of posting different threads on each piece of the cooling system.
I'm going to merge this thread with the other one so it's easy to find out what led to what, and we don't have to start over with each thread.

 

[Kingfam3]

Re: To replace, or not to replace circulator pump

Re: To replace, or not to replace circulator pump

Copy all...my apologies for poor forum etiquette. Main reason I pulled the circ pump was because I wanted to get down to the raw water pump and inspect the impeller. Additionally, the neck of the circ pump was where I had discovered some old impeller pieces that caused my overheating last season. The configuration of my 01 Chaparral 180 SSe is quite poorly designed when it comes to engine accessibility (I have about 6" of clearance from the back seat and the motor and the bench is designed in such away that I can not remove it to perform maintenance without completely disassembling the entire interior) I will get everything back together and test with/without a new T-stat and post my findings. Thanks again!

 

[johnmorgan]

Re: To replace, or not to replace circulator pump

Re: To replace, or not to replace circulator pump

on most pumps there is a little hole around the bottom, water will come out when your bearings go.

 

[Kingfam3]

Re: To replace, or not to replace circulator pump

Re: To replace, or not to replace circulator pump

I couldn't help but continue to think the problem was before the thermostat housing since my first inspection of what was actually hot/cold revealed that the hose in to the t-stat housing from the raw water pump was hot at the top, but cold at the bottom, and cold coming into the raw water pump from the oil cooler/outdrive. I've attached a diagram that illustrates what was hot/cold. In further discussion with my parts guy, he inquired as to whether or not my raw water pump housing was original...he said the original PN had been replaced with a all brass housing. The original has plastic inserts that become lose over time and suck air dropping your water pressure. He told me that the test is, check the housing and if you can spin the inserts by hand, your pump is probably bad. Mine not only spun freely, the output to the thermostat actually wiggled a little bit. I'm installing the new all brass housing this weekend, I will post the results! Anyone else heard of the defective pump housing issues?

 

[rloveless]

Re: To replace, or not to replace circulator pump

Re: To replace, or not to replace circulator pump

Do clear tube test to check for air leaks in the the hoses.

 

[security6]

Re: To replace, or not to replace circulator pump

Re: To replace, or not to replace circulator pump

I couldn't help but continue to think the problem was before the thermostat housing since my first inspection of what was actually hot/cold revealed that the hose in to the t-stat housing from the raw water pump was hot at the top, but cold at the bottom, and cold coming into the raw water pump from the oil cooler/outdrive. I've attached a diagram that illustrates what was hot/cold. In further discussion with my parts guy, he inquired as to whether or not my raw water pump housing was original...he said the original PN had been replaced with a all brass housing. The original has plastic inserts that become lose over time and suck air dropping your water pressure. He told me that the test is, check the housing and if you can spin the inserts by hand, your pump is probably bad. Mine not only spun freely, the output to the thermostat actually wiggled a little bit. I'm installing the new all brass housing this weekend, I will post the results! Anyone else heard of the defective pump housing issues?

I had a similar issue on my 1999 5.7GS. When I went out for the first time this season (with a brand new impeller by the way), I noticed that the engine was getting hot at low speeds. However, everything was fine at higher speeds. I figured that I was sucking air somewhere, but as the engine turned faster the suction increased so at higher speeds the engine had enough water to be cool. When I opened the engine I could see a small amount of water dripping from the output side of the raw water housing, where the plastic and brass meet. I was able to spin the plastic tubes on the raw water pump and move them in and out (away and towards the brass housing) about 3 or 4 mm.

Anyway, I actually repaired my raw water housing with superglue. I felt kind of funny doing it, but superglue is very good for bonding metal and plastic. I figured if it didn't work I'd buy a new housing, but superglue is cheap and easy to try. I put three coats on and the plastic tubes were solidly connected to the brass. I've been out twice since then, including all day on memorial day, and the boat runs cool at low speeds, just like last year. The superglue works.

While I don't recommend superglue for most things, in this case all it is doing is sealing an air or water leak (air on the input, water on the output) and it is not providing any physical support. It worked great for me.

 

[Kingfam3]

Re: To replace, or not to replace circulator pump

Re: To replace, or not to replace circulator pump

I had a similar issue on my 1999 5.7GS... I actually repaired my raw water housing with superglue. I felt kind of funny doing it, but superglue is very good for bonding metal and plastic. I figured if it didn't work I'd buy a new housing, but superglue is cheap and easy to try.

I thought about doing the same thing with the super glue, and after the fact, about how it would operate at higher speeds...I just had SO many issues with overheating frying my sensors last year and racking up the bills, i didn't want to run the risk so didn't even give it the chance to see if it would cool back down at a higher RPM...I figured I'd just replace the part and hopefully not have to worry about anything else the rest of the season, Mike at MPS gave me a good price, so I was happy...good to know someone else out there experienced the same thing! Thanks for the input, I will update the forum with my after actions report.

 

[Kingfam3]

Re: To replace, or not to replace circulator pump

Re: To replace, or not to replace circulator pump

UPDATE:
Got the new housing installed, new t-stat, one new hose (victim of a previous overheat last year and I had to destroy it to get it off of the intake/exhaust manifold inlet)...Started her up on Monday and immediately did a hose check and water is now properly flowing up and into the thermostat housing. Had her running up and down the river around 38 MPH at 4100 RPM's(I could use a stainless prop) and no issues, dropped it down to about 5 mph and plowed for a bit, still no issues, and finally trolling speed for 15 minutes and the temp never climbed above 170 (once it reached 170 it quickly dropped a stabilized a hair under 160, cooler than it ever ran before, even when it wasn't overheating. Thanks again for everyone's insight. This is truly the best forum to be a part of. Everyone really knows there stuff and is so helpful. Thanks again!

 

[Kingfam3]

Re: To replace, or not to replace circulator pump

Re: To replace, or not to replace circulator pump

Alright...boat ran great since te new impeller housing, now all of a sudden it's not happy again...took her out today and had a small water leak at one of the hoses, clamped it down and leak stopped, but after that, anytime I'd go over 2000 RPM's the temp would slowly creep up into the low 200's....I don't know what it could be!?! All hoses seem to b pulling water just fine? Larger hose from t-stat housing to circ pump seems warmer than usual, but that's about it....2K and below runs at 160...any ideas?