Volvo 2002 Raw Water Overheat

[david1993hunter]

Hi, a friend of mine has a Volvo 2002 raw water cooled engine. After 10 mins under load the overheat alarm sounds, but the exhaust water is cold.

The thermostat is not stuck and opens about 67 degrees (meant to be 60), so we removed it as a test. But the same happened, cold water at the exhaust but engine overheating. The thermostat housing is very hot with the thermostat removed, yet the exhaust water is still cold.

Any ideas or anyone experienced this? I thought there could potentially be a blockage, stopping most of the hot water leaving the block, causing it to overheat. I have attached a screenshot of the cooling system.

Thanks in advance

 

[RIBW]

Hi, a friend of mine has a Volvo 2002 raw water cooled engine. After 10 mins under load the overheat alarm sounds, but the exhaust water is cold.

The thermostat is not stuck and opens about 67 degrees (meant to be 60), so we removed it as a test. But the same happened, cold water at the exhaust but engine overheating. The thermostat housing is very hot with the thermostat removed, yet the exhaust water is still cold.

Any ideas or anyone experienced this? I thought there could potentially be a blockage, stopping most of the hot water leaving the block, causing it to overheat. I have attached a screenshot of the cooling system.

Thanks in advance

David, There are many postings on this site on this subject. I suggest you have a look at them and then, if you need further help, post again.
The easiest way, I find, to seach the site is by using google and it's 'site:' feature e.g.
site:ybw.com volvo AND 2003 AND cooling
vary the search parameters to suit your situation.
You could also start with a recent thread
Volvo 2003 water flow
Good Luck
Cheers
Bob

 

[Rappey]

At 67c salt water is crystalising so has the potential to block the waterways ?

 

[scottie]

Toot your flute?
there is a water distribution pipe that runs through the head this can block
you knock the tube out with a wooden spacer have a look at one of the various parts sites to see which way And get the o rings

 

[Stemar]

Presumably you've got a good flow from the exhaust, so we can eliminate a blockage in the accessible bits, or a faulty pump. The most likely thing left seems to be a build up of crud in the head and/or block. I'd get as much water out of the thermostat housing and below as possible, and pour Ridlyme (sp?) or brick cleaner (dilute HCl) in. It's doing its stuff when it fizzes. When it stops fizzing, put more in; when it won't fizz any more, you've probably cured it.

 

[AntarcticPilot]

Toot your flute?
there is a water distribution pipe that runs through the head this can block
you knock the tube out with a wooden spacer have a look at one of the various parts sites to see which way And get the o rings

Yes, that's a potential problem. The pipe in question runs from the water inlet at the front of the block to a pipe that connects to the exhaust elbow at the back of the engine; it is perforated along its length, and the perforation can get blocked. If the perforations block, no water can circulate through the engine block. I'd try running a narrow bottle brush down it first; if the holes in it are blocked (the pipe itself is unlikely to block, and if it did you wouldn't get water out of the exhaust), it won't be a hard blockage and a bottle brush may clear it.

I got very similar symptoms last week, though - and that was bits of water-pump impeller blocking the entrance to the pipe in question. Of course, that was the last bit of the water circulation system that I investigated!

 

[pvb]

Yes, that's a potential problem. The pipe in question runs from the water inlet at the front of the block to a pipe that connects to the exhaust elbow at the back of the engine; it is perforated along its length, and the perforation can get blocked. If the perforations block, no water can circulate through the engine block. I'd try running a narrow bottle brush down it first; if the holes in it are blocked (the pipe itself is unlikely to block, and if it did you wouldn't get water out of the exhaust), it won't be a hard blockage and a bottle brush may clear it.

And it's worth noting that if the distribution pipe is removed, it must be replaced in the correct orientation!

 

[david1993hunter]

Thanks for all your replies, he ended up that evening pouring brick acid in through the thermostat housing, then draining after 10 mins and everything was fine! Must have been the distribution pipe blocked.

Thanks for your replies