Reverse flushing

[kevm14]

Recently I got on a reverse flushing kick to restore heat to my 95 Camaro (150k). The heat warmed the car, but it was not scorching by any means. So I pulled the heater hoses off the water pump and rigged up a neat little job with a garden hose and forward flushed, then reverse flushed the core about 10 times, until I got bored. With everything back together, topped off, bled, etc, the heat is now extremely hot, the way it should be.
In a similar vein, I decided to do this to my other vehicle, a 93 Caprice (206k). Results are not as impressive as the Camaro, but things did improve. It still exhibits a "problem" where the heat isn't as hot at idle, then gets really hot when RPMs pick up. Last year I replaced the radiator and water pump and it still did it.

On both of these cars I have tried RMI-25 as well as a Jiffy Lube forward engine flush (uses the engine's water pump). Both of these things have made marginal, if noticable at all, differences. The thing that made the difference in the case of the heater cores was forward then reverse flushing with a garden hose. On my Caprice, with the heat getting cooler (but still hot) at idle, I am thinking that the engine/intake cooling passages are the remaining ones that need a reverse flush, since the heater core gets its feed off the back of the intake manifold. Other than attack it with a garden hose, is there anything else I can do? Maybe a really strong flush chemical?

 

[kevm14]

Since I can't edit my post now:

How about Prestone Super Radiator Cleaner? I was thinking forward and reverse flush with water until it seemed suitably clean, then do the Prestone treatment and repeat the flushing procedure.

 

[Jelly]

Search "Cooling Fluids & Additives" section for Prestone with my member number.

This From TheTanSedan:

See thread on coolant flush posted by Oldwagon (page one or so); see first post by Jelly.

I hadn't tried this method since before the fall of Saigon . . . cause it takes forever, but boy does it work!

We have a Jeep Cherokee (XJ; 242 cid 6-cylinder) with its little bitty capacity system that -- even with [2] changes prior to the last (at about 58k) -- the outlined method got stuff out even up to the end of the final flush. Much more than the usual tee and garden hose OR the dealers powered machine. Think I used about 13-14 gallons of distilled water, or 3 to 4-gls per gallon of capacity, total; drove several hundred miles in about four days to allow system to cycle cold::hot quite a few times. (Normal business days).

Did this in winter. Heater core warmed noticeably faster than before (just like new).

[ November 15, 2004, 06:23 PM: Message edited by: Jelly ]

 

[kevm14]

Which Prestone product do you think is stronger? the 30 minute radiator flush or the super radiator cleaner that you run for days? In the winter, I really can't run it for days. I'd like to finish a flush in a matter of hours (I could put ~50 miles in an afternoon if I thought it would help).

I read your spiel on the flushing from searching, btw.

Also, how might I mate a garden hose to the much-larger radiator hose?

[ November 15, 2004, 06:49 PM: Message edited by: kevm14 ]

 

[trynew]

It could easily be that the engine coolant passages are coated. I have tried a lot of different products that are supposed to clean the cooling system, but have never been wowed by any of them. A couple of months ago I tried putting a bypass filter with a roll of toilet paper into one of the small coolant lines that connects to the intake manifold. I was impressed with how much gunk I got out of the coolant. I recently took it off and installed it on a second vehicle. I am interested to see what results I get with when I change the TP roll on this vehicle.

While this method really cleans the coolant, I don't know if having clean coolant flowing through the system will eventually remove the buildup that is already there.

 

[trynew]

Another thought I had was that if all else fails, you could consider using a product called Motormax that I think seems to provide faster warm up in my vehicles. Here is a link to a review of it: Review of Motormax

When I asked this forum a while back if anyone knew anything about Motormax, no one responded.

 

[kevm14]

I just read the "review" and while it sounds good, I wonder what it actually is. If it's nothing more than what water wetter is, I'll pass. The thing that somewhat invalidates what he had to say is that the A/C outlet air temps dropped, and he attributed this to motormax. If the author knew anything about the way the radiator and A/C condensor interact, he wouldn't have made that association. It was mere coincidence. But the cooling system temp drops are intriguing.

I will say that since reverse flushing my Camaro's heater core, I get heat as fast as it probably did when it was brand new. It was 35* this morning and there was a thin layer of frost on the car. My commute is about a mile and a half. Before even the first mile mark, I had some heat already. The rear window hadn't even cleared yet. When I parked the car, the engine temp gauge indicated over 160*. Now that's a fast warming up engine. Probably a good thermostat design.

 

[Ray H]

I question the wisdom of toilet paper and any water solution contact. Some of that "gunk" may have been disassociated toilet paper fibrous debris...

 

[trynew]

I don't believe that is the case. Here is the story behind it:

In August, I drained and flushed the cooling system. I then added a container of Prestone Cooling System Cleaner and drove the required hours. I flushed again and installed new coolant.

Then, I happened to read the following post by Ralph Wood, a site sponsor, on the bypass filter forum:

quote:

---

When I bought my 6.9 Ford diesel the coolant looked very clean and green. I put tees in the heater hoses and installed an old Motor Guard M-100. It took about three filter changes before the TP started looking like it hadn't been laying in a mud hole. . . . I thought about using the Motor Guard elmenents because they can handle water without getting soggy. The problem is they are about the same color as the coolant contamination and the polyethylene core is rated at only 175 F. I can remove the core and it works but I like the white elements.

---

I had an old M-100 also, so I installed it in a small coolant line connected to the manifold. After a week, I took it out. It had a lot of rusty colored gunk on it. I put in a new filter and took it out for a 10 minute drive to make sure there were no leaks. I had gotten some paper in the seal, so I had to open it up again. There was already some more gunk on it. I replaced it with a new roll of toilet paper and ran it for several days. This time, the filter was better, but still had some gunk. I replaced it once more, and the next time I checked it, several days later, there was little gunk on it.

If the gunk was really toilet paper, it should have been present every time I replaced the filter and not progressively gotten better. Since my experience also mirrors Ralph Wood's, I believe it really did clean out a lot of gunk. This weekend, I will check on the progress of my current vehicle. If that is the same, it makes me wonder if an awful lot of vehicles are carrying this gunk, which eventually coats the cooling system and causes problems.