citric acid and the heater core. - PeachParts Mercedes-Benz Forum

300DPETE · #1 11-06-2005, 11:38 PM

Does anyone know how well flushing with citric acid cleans out the heater core? I was thinking of replacing mine as a preventative measure (still works), but didn't know if a citric acid would clean this sufficiently. I figure after 24 years, it's probably not super clean inside.

Also, how hard is it to replace? (other than having to shill out $300).

Brian Carlton · #2 11-06-2005, 11:49 PM

Citric acid will clean the entire system and remove the accumulated rust.

However, the heat offered by the heater core is usually sufficient despite the condition of the cooling system. It doesn't make a lot of sense to do a citric acid flush for the benefit of the heater core. If you have overheating problems and suspect accumulated rust in the block and corrosion inside the radiator, then the procedure makes some sense.

It's not a panacea, however. Sometimes the components need replacement and the citric acid simply won't cure the problem.

300DPETE · #3 11-07-2005, 12:04 AM

Quote:

Originally Posted by Brian Carlton

Citric acid will clean the entire system and remove the accumulated rust.

However, the heat offered by the heater core is usually sufficient despite the condition of the cooling system. It doesn't make a lot of sense to do a citric acid flush for the benefit of the heater core. If you have overheating problems and suspect accumulated rust in the block and corrosion inside the radiator, then the procedure makes some sense.

It's not a panacea, however. Sometimes the components need replacement and the citric acid simply won't cure the problem.

Ahhhh. I'm clueless enough that I thought that the engine coolant circulated throught the heater core and that inturn, you'd be reconditioning the heater core with a citric acid flush of the coolant system.

Thanks.

P.S. No known problems with the heater core so far, and the cooling system works fine. I'm just thinking of replacing it as a preventative measure so I don't have to think about it for as long as I own the car.

Brian Carlton · #4 11-07-2005, 12:28 AM

Quote:

Originally Posted by 300DPETE

Ahhhh. I'm clueless enough that I thought that the engine coolant circulated throught the heater core and that inturn, you'd be reconditioning the heater core with a citric acid flush of the coolant system.

Maybe I've misled you.

You are definitely correct in your analysis. If you perform a citric flush, the acid will have a beneficial effect on the internal passages of the heater core.

However, my comments are that the heater core can function well even when it is not in perfect condition. If the remainder of the system is marginal then it makes sense to perform the flush, which will also serve to flush the heater core.

But, if the system is working well, it does not make sense to go through the effort of a citric acid flush and/or replace the heater core.

Would you make the effort to replace the evaporator just because it is old? Now here is a component that could use a good cleaning. But the cost and time is very high.

300DPETE · #5 11-07-2005, 12:36 AM

Quote:

Originally Posted by Brian Carlton

Maybe I've misled you.

You are definitely correct in your analysis. If you perform a citric flush, the acid will have a beneficial effect on the internal passages of the heater core.

However, my comments are that the heater core can function well even when it is not in perfect condition. If the remainder of the system is marginal then it makes sense to perform the flush, which will also serve to flush the heater core.

But, if the system is working well, it does not make sense to go through the effort of a citric acid flush and/or replace the heater core.

Would you make the effort to replace the evaporator just because it is old? Now here is a component that could use a good cleaning. But the cost and time is very high.

Agreed, but luckily that's been replaced (the evaporator and other AC components by the previous owner). If I replace the heater core, I essentially have a new climate system, both hot and cold.

As for the engine coolant system needing a citric acid flush, when I recently installed an inline block heater (in the hose running from the bottom of the radiator to the thermostat housing), I noticed a substantial amount of rust in the old hose, so I thought a citric acid flush was in order. I'll also be changing out the water pump, monovalve, and thermostat while I'm at it.

Brian Carlton · #6 11-07-2005, 12:40 AM

Quote:

Originally Posted by 300DPETE

As for the engine coolant system needing a citric acid flush, when I recently installed an inline block heater (in the hose running from the bottom of the radiator to the thermostat housing), I noticed a substantial amount of rust in the old hose, so I thought a citric acid flush was in order. I'll also be changing out the water pump, monovalve, and thermostat while I'm at it.

I had a decent amout of rust on the top hose for the SD. But, the coolant that exited the block had no rust in it, so I'm not too worried about it. I think the citric acid flush should be reserved for those cases where the system has been neglected for many years. There is quite a bit of effort involved in eliminating all the acid after introducing it into the system. Furthermore, I understand that a degreaser is required before the introduction of the citric acid. It's quite an involved process.