Volvo Penta 2003 Overheating

Wanting to take care of this overheating issue right away I came back to the boat on Monday following our weekend.  I started the engine and found that no water was coming from the exhaust and within a few minutes the exhaust elbow was too hot to touch again.

I’ve been researching the issue online and I’ve read 100s of posts on various websites saying that the issue could be caused by anything from clogged raw water pipes, to a bad heat exchanger, a bad thermostat, a bad impeller, a clogged raw water strainer, plugged raw water inlet, plugged exhaust elbow, etc… I already did the easy things like checking the impeller, cleaning the raw water strainer and checking the raw water intake to no avail.  I suspect it’s either the heat exchanger or a plugged exhaust elbow.

I started out by removing the heat exchanger as it’s looking in pretty rough shape.  I’ll take it somewhere to get it rebuilt this week.  John, the previous owner of Treylya, mentioned that it hadn’t been serviced in 5 years and it shows.

The old heat exchanger looks to be in pretty rough shape
The old heat exchanger looks to be in pretty rough shape

I blew into each tube coming off the heat exchanger to see if they were blocked and air passed thru each pipe except the one leading to the exhaust elbow.  I blew until I was red in the face and I couldn’t force any air thru the pipe.  Hmmmm…  Something’s not right here…  I decided to take the exhaust elbow off and found it to be plugged with scale and rust…  Not good…  The inlet at the top of the elbow where the water from the heat exchanger enters the elbow was completely blocked by crud and over the years of heat and pressure it was as hard as iron.

The water inlet on the top of the exhaust is completely plugged
The water inlet on the top of the exhaust is completely plugged

The water which was suppose to come into the top inlet was suppose to be flushed thru the head of the elbow (keeping it cool) and injected into the exhaust pipe but all water inlets were fully or partially blocked and the water outlets were non existent…

Exhaust Elbow
Exhaust Elbow
The pipe in the Exhaust Elbow where the exhaust passes wasn't too bad...
The water outlets in the Exhaust Elbow where water is ejected were completely covered…

I took the heat exchanger and exhaust elbow to a local marine shop (Gartside Marine Engines) and they showed me where it was blocked and suggested that the elbow probably needed to be replaced but that I should bring the exchanger to a local auto transmission shop and get them to rebuild it.  I followed their advice and ordered a new elbow and dropped the heat exchanger off to Townside Auto in Victoria.

By the end of the week the parts were ready so I picked up the new elbow and couldn’t believe the difference…  This was probably the main source of the issue as the flow of water was blocked and therefore no water was circulating and therefore the heat exchanger couldn’t do it’s job of transferring heat from the engine.  The new elbow should make a big difference.

Comparison of the old exhaust elbow and the new
Comparison of the old exhaust elbow and the new

Next I dropped over and picked up the new heat exchanger and it looked brand new.  I’m ecstatic about what a great job the shop did to rebuilt it.  Initially I was concerned that the exchanger was ruined so I priced a new one and a new Volvo replacement part was $2100.  The rebuild cost was only $200.  I’m so relieved…  I installed it and moved to the exhaust elbow.

The rebuilt heat exchanger looks as good as new... I'm very pleased...
The rebuilt heat exchanger looks as good as new… I’m very pleased…

Before reinstalling the elbow I checked the coolant and raw water pipes and found that the pipe which goes from the heat exchanger to the elbow was about 90% blocked.  There was built up of scale and rust and only a small hole, about the size of a head of a match, remained open…  In a previous email John mentioned that the water flow was always low on Treylya but he never determined why.  I think I found the issue…  I grabbed a screwdriver and scraped it out and after about 30 minutes I had it opened up pretty good.  That should help…

The next thing that I thought I would check was something I read online about a pipe that runs thru the head with small holes in it that sprays water into the head to keep it cool.  This is called the “water distribution pipe” in the Volvo Penta Workshop Manual.  Sometimes the holes get plugged with scale which can lead to overheating issues.  I took the connecting tube off the end of the pipe and shone a light in to check the holes.  They all looked pretty good but I took a small piece of wire and poked each one to ensure they were clear.  All was good so I put the tube back on the end of the pipe.  One less thing to worry about…

Clip from the Volvo Workshop Manual...
Clip from the Volvo Workshop Manual…
Tube which carries water thru and cools the head looks clear
The pipe which carries water thru and cools the head looks clear

Next was to reinstall everything…  I purchased a few steel brush heads for the drill and some sandpaper and spent the afternoon cleaning rust from the engine.  Once the exhaust area was clear of rust I cleaned and spray painted the surfaces.  To reinstall the elbow I installed the exhaust tube, placed the gasket onto the block, then lined up the elbow and screwed the bolts down.

Preparing the engine block for painting
Preparing the engine block for painting
About to reinstall the exhaust elbow
About to reinstall the exhaust elbow

The old bolts looked pretty tired but it was getting late and I just wanted to get the elbow back on so I decided to reuse the same bolts.  Bad idea…  The first 3 went on pretty good but the forth twisted off as I was applying the final bit of pressure to it…  Oh no…  WTF!  How the heck did I make such a dumb mistake?!?  It was the end of the day and I was tired from wrestling with this all day so I decided to leave it for the morning.  Groan…

I ended up twisting off one of the elbow bolts
I ended up twisting off one of the elbow bolts

Next morning I stopped by Home Hardware to pick up a screw extractor.  I was feeling apprehensive about what lay in front of me as I drove to the boat.  I removed the three bolts and to my relief there was still about 1/2 an inch of the broken bolt sticking up when I removed the elbow.  Whew!  That should make things easier…

Luckily the bolt was partially exposed making it somewhat easier to remove
Luckily the bolt was partially exposed making it somewhat easier to remove

I worked at the bolt for a few hours using Liquid Wrench and a pair of vice grips…  Pitting a software developer against a broken, corroded, seized head bolt was a bit of an unfair fight and there were many phone calls to my brother Doug, several Hail Mary’s and various small dents in my knuckles but in the end it came out.  Whew…

After much huffing and puffing a finally got the little fella
After much huffing and puffing a finally got the little fella

For some reason whoever installed the exhaust elbow used zinc plated bolts and with the salt water environment they were pretty badly corroded and the one that broke was narrowed in at the middle of the bolt.  Being lazy I used it anyway and it broke…  Lesson learned…  I ran out and picked up some stainless steel replacements…

I purchased new stainless steel bolts to replace the old rusty ones
New stainless steel bolts to replace the old rusty ones

I reinstall the elbow, opened the raw water shutoff and was ready for the initial live test.  Deb monitored for leaks with a flashlight and I ran up and turned the key.  After a few seconds she fired up and apart from a few minor leaks (where I forgot a seal) it appeared to be working fine.  We let her run for about 10 minutes and the exhaust elbow and engine remained cool.  I put her in gear and rev’ed up the motor for about 25 minutes and all was good.  There was a nice heavy flow of water coming out with the exhaust and things remained cool.  Wahoo…  Looks like the overheating issue is solved.

I’m really enjoying getting to know my new boat better and troubleshooting the various issues.

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