Cooling System woes...

[korn2822]

So I get this great deal on a 91 240 and have sunk double into it what I paid for the car...goin broke here LOL.

Anyways.... from what I can tell, this car was running with a coolant leak and the previous owners were just putting water in it. I also think the car sat inoperable for longer than they implied. I know it overheated hardcore because the head gasket was blown, car was lacking about 100psi of compression in all cylinders. Now the problem...rust in the cooling system.

Does anyone know a good additive or procedure to combat the rust issue, or do I just roll with the punches?

[compactfean]

Ive dealt with rusty systems like that and the best thing to do is remove the t-stat and upper hose and lower hose and run a garden hose through the radiator and the block until all is clear. This can sometimes take a very long time. After that put the t- stat back in and run the upper hose to a bucket and cap off the radiator. Fill the radiator with water, start the car with heater on full blast and keep the radiator full when its running. When the t-stat opens check to see what color it is coming out. When it clears out then you can drain out all the water and full with 50/50 (i would actually go a little heaver since there will still be water in the system) regular antifreeze has additives to prevent corosion, rust,etc so once the system is clean your back to normal.

[korn2822]

Good advice, thanks. I'll give it a go and see what happens.

[esd51918]

Your first note implies that the previous owner had been running straight water for coolant. If that was the case then you might want to take a good look at the water pump as well. Antifreeze also serves as a lubricant to the water pump. Running straight water can contribute to a premature failure of the water pump.

[korn2822]

I appreciate the heads up about the water pump, but I;m one step ahead of you there, its rusty as all hell too. car also had no thermostat in it so I will remedy that too. Thanks for the tip though.

[jaredta1a]

You could take the thermostat out not a bad idea at all depending on how much rust you have, but I would keep it in and disconnect both heater core lines, this closes the circuit and will clean the block out better, flush both ways and then both ways through the heater core, then open the drain on your rad and flush from the top down, don't forget to change out your pressure cap on your radiator, if its not pressurizing correctly you can blow another head gasket

[korn2822]

The Rad is brand new aluminum, not installed yet, so plus there....you're saying disconnect the heater core, flush upper and lower ends separately and then the same for the heater core?

[compactfean]

it doesn't really matter how you flush it. It send like the consensus is to flush flush flush until its all clear before you spends money on coolant. Alot of people have different ways but they are all pretty similar. Which ever way you comfortable with as long as it comes out clean.

[nefarious300zx]

personally what i do to clean out nasty old coolant systems is use some CLR and run it through the system, not for very long mind you just a few minutes as the CLR is pretty tough stuff. drain it and then run some coolant flush through it to remove any more residue and also clean all the clr out (you can get it anywhere). then take a look inside the coolant passages you will be surprised it works great. never had a problem from it.

[compactfean]

See I would beg to differ with that process. At my last job I had a claim that my store had to pay out on, (yes it went to court) because we did a flush on a very rusted system with a flush kit and within 24 hours the head gasket blew. We even had the owner of the company pay an inspector to see if it was our fault and when all was said and done it was our fault because we shouldnt have recomended such an abrasive service to a system that neglected. Pretty much what they said was that using the cleaner cleaned out what was holding that thing together which does make sense. That's why I would just use water, get it super clear and let fresh coolant take care of protecting. Just my .02.

[compactfean]

Granted this was the only problem we had like that In the 5 years I worked there out of 1,000's of flushes but any thing can happen.

[jaredta1a]

This can defiantly happen but I would suspect on a car with previous head gasket damage. As a tech for about 6 years now I don't know how many coolant flushes I have done in the shop with the machine and 9/10 are extremely neglected systems that have never been touched and that other 1/10 is cars that are dangerous to flush, sometimes you can see evidence of radiator stop leak, oil residue, coolant residue, (looks like mud) really bad rust so on... In a shop I bring the customer out and explain the possible dangers of their neglected system and suggest new parts on those cars. Very few people spend money on the cooling system, me on the other hand... I'm working on a after run coolant pumps wired in on a time delay for my 2+2 300zx tt and 240sx sr20