1st surprise on my 91 Trofeo project. I was so focused on other issues with the car while looking it over to purchase, I did not check the radiator coolant. So the picture tells the tale. I did some research and found this sludge is not uncommon, especially if green and orange coolants had been mixed in the past. Will flushing out the system and using correct coolant work in the meantime, or am I looking at my 1st big blow to my project budget by having to replace the radiator and heater core? Any advice would be appreciated.

 

I'd start by flushing the system out. It may take multiple treatments.

 

You're going to need to flush that out with something that dissolves that kind of goo.

What that something is, I don't know.

I would recommend scooping as much of it out as possible and trying different solvents on little bits of it until you find something that dissolves it well, but is unlikely to hurt the rest of your cooling system.

Candidates for harmful chemicals would include acetone, lacquer thinner, and strong acids and bases (like battery acid or lye).

Candidates for less-harmful chemicals would include rubbing alcohol (isopropanol), wood alcohol (methanol), drinkin' alcohol (ethanol), and weak acids or bases (vinegar, radiator flush compound). Home cleaning agents like Fantastik or Formula 409 MIGHT be a possibility, but if you use these, you would have to flush ALL of them out of the system, as any foaming or sudsing AT ALL would prevent the cooling system from working.

Good luck!

- Eric

 

Maybe try CLR?

Pat

 

I'd lean toward bases like Drano, BUT, you would want to be able to run the engine, both to warm it up for better flushing, and to remove what has been flushed out.
Collect what is flushed out for proper disposal.

 

I successfully cleared out the heater matrix and radiator of my Nissan last year with Toilet Duck, a proprietary brand of toilet cleaner.
I filled them up with it, left it overnight, then flushed out enormous quantities of crud.
Then I had a heater working better than it ever did since I had owned the car.

I don't know if it will have harmful effects on rubber hoses, but it might be a good idea to replace yours anyway unless that has recently been done.

Roger.

 

Just be careful, because lye (sodium hydroxide, NaOH) is VERY reactive with aluminum (ever spray Easy-Off oven cleaner on the aluminum trim of a stove?), so if you have an aluminum radiator, it could be all over if the concentration's too strong.

And "proper disposal" of lye is just dilution: Spray it down the driveway really well with the hose.

- Eric

 

Lye and aluminum create hydrogen gas, very explosive.

 

Be careful with vinegar, I did that once, worked well but if you
have any pinholes that were plugged, it will open them up.

 

I say if vinegar or anything else unplugs pinholes it's time for a recore anyway.

Roger.

 

Thanks Everyone for the tips. I'm going to try a few of the weaker chemicals to start with and get as much of the crud out of the radiator I can. Then run some Radiator Flush through the whole system. I watched a video that showed taking the thermostat out of the housing and run the flush chemicals through the system at operating temp with the heater on high for 15 minutes at a time, let it cool and drain. I was told to repeat this flush method along with distilled water until clear of any color or crud comes out of the lower hose. It will take some time, but I want to try something before having to buy new parts.

 

Well my 93 Buick radiator looked that way a couple of years ago and it was because the tranny cooler blew in the radiator and antifreeze and tranny fluid mixed together looking a lot like what you have in the picture . The smell is the tell tale sign , I could smell a strong oily smell when I put my nose near the opening on the radiator , it was quite obvious what happened in my case .

 

Oldsguybry made me think of your other post about transmission woes, particularly the discolored oil.
Possibly the two faults are connected?.

Roger.

 

The sludge in your radiator looks to be similar to either of these scenarios:

The previous owner tried to hide a leak in the cooling system be adding using some unknown "snake oil" additive, or the trans cooler is leaking into the radiator; either way, you need to find the cause of the problem, BEFORE you attempt any repairs!

How does the transmission fluid look? Usually, a leaking radiator cooler will flow BOTH ways, depending upon temperature/pressure; if the transmission is contaminated, you have a serious problem, depending upon how long this has been going on!

 

I checked the smell and feel of the sludge. Not Oily or smelling like oil. It has a slight "sweet/old" smell to it. the Transmission Fluid is dark, but looks to be old and worn out liquid. No burnt smell. The Transmission will not shift out of second and sometimes acts like it wants to, but just quite can't when I test drove it. The previous owner had let the car sit (according to his story) for almost a year because of the transmission problem and ran the engine weekly to keep the battery up. I asked if he had changed the transmission fluid, oil or Coolant since he had the car for 4+ years. He said he had the oil changed but had never changed anything else except a few years ago added some coolant because the car overheated. I asked if he knew the original color of the coolant, and he could not remember. So he may have mixed Green with Orange.

 

Is this an "old wives tale" fix? I saw on the internet some people have used a lemon juice trick to flush the radiator. Supposedly the acidity of the lemon juice and distilled water mixture will breakdown the sludge and make it easier to rinse it from the radiator.

 

I would use the heavy duty flush that is ok for aluminum then take out the radiator and get it checked and cleaned by a radiator shop. I would also look at every hose and hose connection. Try to make them leak. Now is the time to find out. I do not like that orange coolant that GM has been using. It mislead people into thinking they could let the radiator service be avoided. Your radiator should be at minimum drained and fresh coolant every two years. Keeps the acid level down. and it is not very expensive. Changing hoses and heater cores sucks and can get spendy.

Just my two cents.

Larry