Front heater core flushed with CLR now producing 135 degree vent heat.

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SUMMIT CRUISERS

SUMMIT CRUISERS

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Edmond, Oklahoma
On our 92 the front heater has been lacking this year. Usually it will get up to about 100 to 110 degrees F through the vents.
I've tried flushing on the front side of the T going to the heater cores with no success. The rear heat always has worked great but the front not so good.

Here's what I did:

Removed the T and blocked off the bottom line going to the rear heat.
Reverse flushed the front core through the clear vinyl tubing with water and blew out any residual I could with my air compressor.
Filled the top inlet going to the front core with about a bottle and a half of straight CLR. Probably a bottle would have worked.
Let it set for 2 hours.
Flushed it and the rear core all out with water.

In the past when I flushed it out in front of the T, I believe the CLR and flushing were going through the travel of least resistance which in my case was the rear heater core.

Here's a pic of process: The brass drift was used as a plug for the rear heater core. I felt it not necessary to take apart the T on the driver's side of the water valve.

Got Heat now!
92 heater cores 002.webp
 
Kernal said:
What came out when you flushed the heater core?
Click to expand...

It was hard to tell but I did notice some black specs, some tan/brown colored stuff probably stop leak and white. The CLR seemed to disolve the contaminates.
Not sure if the white was calcium/hard water or the CLR. The CLR when flushed and blown out appears as white/foamy.
 
I had the same pitiful heat, not hot just warm even with a normal operating temp. I just followed the above procedure, complete with the CLR soak for 2 plus hours. Heat works awesome now. The only thing I did different was flushing the core both directions. I too was worried about the core starting to leak. However, no problems, just nice hot air out of both heaters. :D
 
Tracking this is an old thread but does anyone know the inner diameter of the heater hoses? Going to acquire the parts to do this hopefully this weekend but want to make sure I get the correct adapters.
 
@jdayment

Just did this tonight but have a 1fz so not sure if the same as yours.

I skipped the clear vinyl which would likely be cheaper and just bought 5/8" heater hose (6' but 8-10' would have made it easier to clear the fenders) and some brass barbed hose repair fittings and it worked great. Removed OE lines, cut heater hose in half, and attached direct to brass hard lines. My rear heat is bypassed so a little different process than yours perhaps.... or didnt have to worry about plugging the rear outlets like OP did.
 
jfz80 said:
@jdayment

Just did this tonight but have a 1fz so not sure if the same as yours.

I skipped the clear vinyl which would likely be cheaper and just bought 5/8" heater hose (6' but 8-10' would have made it easier to clear the fenders) and some brass barbed hose repair fittings and it worked great. Removed OE lines, cut heater hose in half, and attached direct to brass hard lines. My rear heat is bypassed so a little different process than yours perhaps.... or didnt have to worry about plugging the rear outlets like OP did.
Click to expand...
Awesome thags a better idea dont know why i didnt think of plus can never have too much hose laying around
 
izzyandsue said:
Nope. What kinds of issues are you seeing?
Click to expand...

I haven't tried it, but may be trying it depending. Just wondering if the people that tried this 6 years ago all of a sudden found their Heater Core presenting issues due to the clr as other posted had noted concerns of that type.
 
If you have concerns of using chemicals, you can always use water only to do a reverse flush and a flush. Should still help the crud out. Remember to use distilled water to rinse the tsp water out.
 
I had no heat whatsoever. Flushed with water first and that did not fix it, then i did it again with CLR and finally got blazing heat! I just made sure to thoroughly flush the CLR out with water and I have had no issues whatsoever. ( did a final rinse with distilled water and blew it all out carefully with he air hose) Also i didnt see any big chunks of debris or anything like that... just brownish discoloration, but obviously there was some sort of blockage. Just glad its not cold as balls in the winter anymore
 
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Having similar issues with my '92. But a little history first. When we bought it a few years ago in November and parked it until spring, we discovered a busted rad and block in the spring. It was my bad for not checking when we bought it, but the previous owner only had straight water in the system and no thermostat, and after a harder winter with temps well below freezing those parts let loose. The engine still ran just fine as it was an external crack, but we had to add fluid every other day or so. When we changed the rad and installed a t-stat we noticed how dirty the "coolant" was, so I flushed the system and got what looked like straight mud out. Took about 4 flushes to run clear. Then we swapped in a 2FE. That was about 3400 miles ago. Everything has been running good and good heat out of heaters.

Now this winter has been extra cold and I noticed a few weeks ago the rear heater was not producing any heat until after about 30 mins and some uphill driving, and even then it would go lukewarm after a minute. Just today the front heater started running cold, it didn't do that last time I ran it, and it's been cold outside for awhile. Engine temps on the dash gauge come up to normal right away and don't fluctuate. I suspected t-stat, but the hose on the rad side of t-stat was nice and hot and the rad had pressure when I burped the cap, so I'm thinking the t-stat is good. Heater valve on firewall appears to be functioning properly. So I'm left with thinking the cores are plugged, and rather quickly.

Will have to do the flushes as mentioned here on the site, but would like to use something stronger than CLR. So one question I have is does anyone know what the heater cores are made of? If copper or brass, then that is good. But is any aluminum, then not good. Reason why, is I have flushed old (like early 70's old) FJ40 cores that are brass with straight muriatic acid. Muriatic eats aluminum, but not brass or copper, and does a terrific job of cleaning plugged cores with hard deposits. Had a core once that was over 75% plugged, came out like new after 3 flushes with muriatic.
 
It sounds like yours may have an air pocket in the heater core. That would be the easiest fix. Raise your front drivers corner where the cap is higher than the heater valve. This may require it be in a ditch at an angle or a big floor jack on the front corner. Take off the radiator cap with engine cool and start and idle truck with heat lever all the way hot. Add AF as needed to top off.

Not sure about the cores. I do know that the fins are aluminum though. Maybe the cores are also?
 
I would not use anything stronger than CLR. Even CLR if left too long can have a detrimental effect. Since you can't control what the acid will attack once it is in the core, you can erode both the crust build up and the metal, and up with a weaker system. Maybe do 2 or 3 rinses with CLR with decreasing residence time, i.e. 12, 8, 5 minutes and observe how dirty the results are. Once you are getting clean rinses, in both flow directions, you should be fine. Might be a good idea to replace the radiator hoses as well while you are doing all that work. Best of luck, I have a good friend in Prince George working through a similar problem on his 80, you do have an amazing snow year in BC! Feel free to contact me anytime.
 
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