volvo 2002 exhaust elbow and water pump

[saltyrob]

Hi Folks,

I am thinking of removing the exhaust elbow and giving the inside a clean as I understand that it can became clogged and reduce cooling water flow. Do you undo the bolts on top of the elbow and just lift it off the engine or is there more to it.
Also to remove the water pump do you just undo the bolts on the pump housing and pull the assemble out of the engine.

I have the manual but am a bit careful with most things mechanical

Many thanks

Robert

 

[EdEssery]

That's correct in both cases. You will probably need a new gasket for when you bolt the exhaust elbow back down. You will need to remove the cover for the thermostat first though as this bolts into the front of the exhaust elbow. When I took mine off the bigger problem was separating the exhaust hose from the elbow.

Regards,

Ed

 

[Birdseye]

I was warned that the elbow can corrode and that I might have difficulty in re-sealing since the joint faces arent very thick. As it happens, I dt have problems, but I mention it to you since you dont really sound to have a reason for taking the risk

Why the pump? Have you got a cooling problem?

 

[JackFrobisher]

I recently had to replace the seals on the heat exchanger on my 2003 (similar construction) and decided to do a general clean up of the water system at the same time. I did think about taking off the exhaust elbow but in the event, after I had removed the bolts, it wouldn't budge so I left it. I did however notice that the point where the cooling sea water entered the elbow was almost completely blocked with scale. To be expected I suppose because of the deposition of calcium and salt at the point where the water enters the hot exhaust gas and most evaporation will take place.

I cleaned this out, which only involved removing the pipe feeding it from the heat exchanger and giving it a poke, and the water flow from the exhaust is now noticeably increased.

 

[andy_wilson]

Not sure about Ed's reply below. From memory the exhaust elbow is held on by 4 bolts, and has two bypass pipes set into it, one straight from the thermostast housing, one from the back of the cylinder head which has a composite twist in it.

It would make sense before you start (as you may need them before you finish) to have a new thermostat and exhaust elbow gasket, plus a fist full of the rubber seals Volvo use all over the engine to connect these pipes. I also destroyed my thermostat trying to remove it, and some would say having a spare on board is not a bad idea, the new thermostats are a bit different to the old ones but are fully compatible. It's important to get the right one (salt / fresh water cooling).

Removing the rear bypass pipe may be the hardest bit, dependent upon the quality of the rear access. All of these pipes have a flange with a rubber o-ring and are held in place by a simple forked flange. Just remove the 10mm (approx) screw and flange, and pull the pipe out.

The bit that gets most blocked is the distribution pipe which is inserted into the rear of the block, where the bent pipe leads to the exhaust elbow. In an old engine you are unlikely to remove this with the head in situ, but chemical cleaning will do the trick.

I drained down in situ, removed thermostat and exhaust housings, filled slowly with 5% Hydrochloric Acid (brick and masonery cleaner which was 10% - diluted 50:50). While the engin innards fizzed I dropped the two castings in a bucket of the stuff. The engine needed a couple of drains and re-treatments before the fizzing ceased. All parts need a thorough rinse afterwards and you need to take great care to defend yourself and adjactent boat parts from splashes.

Can't remember about the pump housing, but that won't need cleaning though the rear seal can weep a little. I think there is a locking ring that needs releasing from the shaft to remove it

 

[saltyrob]

Hi Andy,

Can you clarify which bit of the exhaust/ housing should be removed.Our engine is raw water cooled.

Many thanks for all your responses

Robert

 

[Stellina]

I dipped my exhaust elbow from a 1986 2001 in acid as you describe and the result was really good. As with JackFrobishers comments the inlet was really scaled up but also the elbow had corroded so that the flat mating surfaces for the gasket and the cooling pipe from the head block were not good enough for a good seal. I split a gasket and used an additional half to get a better seal.

A word of warning... be careful with the torque on the elbow, thermostat and cooling pipes flange bolts, especially the latter. If the elbow mating surfaces are not good and you strip the threads then you have a hell of a job to keep them tight. I had to wedge the flange for the thermostat inlet because the bolt would not give enough pressure due to thread damage. This was OK but meant to check or change the thermostat was not something done easily any more.

Andy