The Stovebolt Site Forums The Shop Area Engine Shop Coolant Filter

My 235 seems to cruddy up its coolant after a flush…way too fast. This is all in spite of several flush “hacks” I’ve tried here. Muriatic acid, blasts of compressed air through block drain, etc. I get crystal clear water draining, and within a few months it’s gross again. I also suspect the modern formulation of traditional green coolant has been neutered by regulation.

Would one of the big spin on coolant filters like used on diesel engines be of any use? I wouldn’t see this as a permanent measure. Just thinking given some time all the crap in the bottom of water jackets would find its way into suspension and into the filter.

But that’s all just theory with no practical experience with coolant filters.

I installed a coolant filter years ago on a gas V8, the chemicals in the filter were way too high a concentration for the small volume of the pickup truck system. Whatever the chemical was, it started to cause oxidation on aluminum parts, I removed the filter and mount.

That is odd. Are you sure there is not a leak somewhere?

You mean like a head gasket or such? That thought has occurred to me. But I sure don’t have any other signs or symptoms of that.

If you get the block pretty well cleaned out and you're using a good quality of anti-freeze in the right proportion, you should not have much crud. I suggest getting an overflow tank to keep the radiator always full. Air in there isn't your friend.

I have one.

Maybe run just water for a few days and check.

Probably not what you want hear, but pull the water pump and block drain, then with a RED tip on a power washer, spray down through the water pump hole for awhile. Switch to the drain hole and back flush out the water pump hole. Your cleaners may have all the crude loosened, but it can't get out with just a water hose. The Red pin-point washer nozzles really get into small areas and blast it loose.

Most of the diesels I am around quite using the filters years ago, I haven't seen one since early 2000 and even then they were rare. And yes, they do have additives in them for cavitation prevention.

Good luck, Nathan. Last time I cleaned my block I removed the water pump, poured CLR in there until it almost poured out through the water pump hole and left it for a couple of days. Then with a straightened coat hanger with a little L bent at the bottom I worked to loosen all the junk in there (it will be the worst at the back cylinder which is not easy to reach), left it another day and drained/neutralized it, discarded that stuff at the city's waste place and repeated this procedure. Once that was done it cooled better and has run pretty clean. I don't own a power washer, so I can't speak about that, but Joe's suggestion might be good. I also used some cleaner made by Prestone. I may as well have run some orange marmalade in there for any good that stuff did.

Are the diesel coolant filters more of a chemical/ionic filter and not so much a physical filter media?

I might just do a yearly flush and live with it. It doesn’t seem to hurt anything other than my pride. Truck runs cool other than on the hottest days when not moving at a long light.

The power washer thing probably needs done, but I’d likely wait until I’m ready to do the 216 water pump adapter thing. Running a short shaft 235 pump now and it works plenty good enough for me.

I might also do the combustion gas test thing just for a little peace of mind. I just don’t have any milky oil, no overheating, no steam-cleaned plugs (last I looked).

Some filters for diesel application have chemicals in them (called supplemental coolant additive) to prevent cavitation, but filters are also available with no SCA (NAPA #4070 or equivalent.) I have one of those on my 7.3L. Once it filters out the initial casting sand, etc. they come out pretty clean when changed out.

It sounds like you might need to do a pretty aggressive flush like Jon G did. The rear of the block gets pretty gunked up. When I first got my engine, i pulled all the core plugs and scraped out whatever gunk I could, then went at it with a pressure washer. The rear plug behind the bell housing was nearly filled with gunk.

One other suggestion: you can purchase (via Amazon or elsewhere) 45% vinegar or crystalized citric acid (either of which can be mixed with water to any strength you want). Either of those are very tough on rust. In fact I wouldn't leave either in the block for more than an hour and then flush with clear water. Both of them should be used in a vented area (naturally). If you use the vinegar at full strength you might check around to see what some "experts" suggest.

I use an aluminum radiator, a thermostatically controlled high cfm Spal fan and an extra pusher fan for the A/C unit in front of the radiator. I will tell you the electric fan for the A/C runs on a trinary switch whenever it is on but the main puller fan shuts off when enough air flows through the radiator naturally. One thing is the engine is much quieter without the stock fan. At least mine was notably quieter at all speeds. Good luck!