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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / February 2005After Coolant flush still heavy sediment
After a $130 Coolant flush on a GM 3.8L at 82,000 it looked the same the next day from the radiator cap. Lots of sediment and old dirty looking coolant. Now it was 20yrs ago for my last self performed flush on a 78 Nova, but it seems to me the coolant looked clean and new afterwards. Of course back then it was every 30K instead of this 150K-coolant change. Dealership informed me with new cars, the coolant always looks dirty with sediment, after a flush. Too difficult to clean completely and only their high tech machine can do it. Here I thought the 3.8 was a 30yr old design. I am wondering if they just drain and refilled or are these "new" engines just impossible to flush? > After a $130 Coolant flush on a GM 3.8L at 82,000 it looked the same > the next day from the radiator cap. Lots of sediment and old dirty [quoted text clipped - 12 lines] > I am wondering if they just drain and refilled or are these "new" > engines just impossible to flush? Most dealerships now use a "flush machine". They unhook a hose, usually your top radiator hose and hook the machine up to it. As your thermostat opens up, the machine exchanges your old coolant for new coolant. When the process is complete, the machine beeps and the technician unhooks the radiator hose from the machine and hooks it back up to the radiator. Your engine and radiator now have new coolant. The problem with most cars is that the radiator cap is not on the radiator, but on your coolant recovery tank. Most flush machines (or technicians) will not flush the coolant tank and what you see when you take the cap off the coolant recovery tank is still the old coolant. Like it or not, the flush process does not take out 100% of the old coolant, especially in the recovery tank. > The problem with most cars is that the radiator cap is not on the radiator, > but on your coolant recovery tank. Most flush machines (or technicians) > will not flush the coolant tank and what you see when you take the cap > off the coolant recovery tank is still the old coolant. Like it or not, > the flush process does not take out 100% of the old coolant, especially > in the recovery tank. The recovery tank does accumulate a lot of filth. They are easy to flush, but not so easy to get 'clean enough to eat off of'. But, as far as I know, the radiator pressure caps are still right on the radiators, and they come off relatively easily. Remove the cap, the lower hose, and the upper hose/thermostat housing, and you can flush both block and radiator with a garden hose. Exhaustively. And it doesn't cost $130. > The recovery tank does accumulate a lot of filth. They are easy to flush, > but not so easy to get 'clean enough to eat off of'. > > But, as far as I know, the radiator pressure caps are still right on the > radiators, > and they come off relatively easily. The original poster did not say the make or model, but with the mileage stated, it is probably at least a few years old. Anyway, take a look at a lot of late model cars at a dealership. The radiator caps are on the recovery tanks for most late model cars. This makes it harder for the do-it-yourselfer to flush the radiator. (I'm not saying that it can't be done. It's just harder) It also makes the radiator hoses more expensive as they "Y" off to join both the engine block and the recovery tank with the same hose. With that in mind, the dealership probably did a power flush on the vehicle. They just didn't flush the recovery tank. > > The problem with most cars is that the radiator cap is not on the > radiator, [quoted text clipped - 14 lines] > you can flush both block and radiator with a garden hose. Exhaustively. > And it doesn't cost $130. No radiator caps on GM 3.x series. > > > The problem with most cars is that the radiator cap is not on the > > radiator, [quoted text clipped - 16 lines] > > No radiator caps on GM 3.x series. '96 Regals (3.8L V6) certainly have caps. The $tealership just lived up to it's reputation, you got burned. Man the bullshit they try to pass off to customers these days..... Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's > After a $130 Coolant flush on a GM 3.8L at 82,000 it looked the same > the next day from the radiator cap. Lots of sediment and old dirty [quoted text clipped - 12 lines] > I am wondering if they just drain and refilled or are these "new" > engines just impossible to flush? > After a $130 Coolant flush on a GM 3.8L at 82,000 it looked the same > the next day from the radiator cap. Lots of sediment and old dirty [quoted text clipped - 12 lines] > I am wondering if they just drain and refilled or are these "new" > engines just impossible to flush? There may be some dead spots in the water jacket that it is difficult to flush, but it wouldn't be hard to do better than what they apparently accomplished. For $130, I think you should have gotten a much better job. Typical dealership crappola. I suspect that the dealership actually did flush it, it's just that in order to get the recovery tank, it needs to be removed, and they didn't do that. It only takes a very small amount of dirt to make it look just as dirty as it was before. > I suspect that the dealership actually did flush it, it's just that in > order to get the recovery tank, it needs to be removed, and they didn't > do that. It only takes a very small amount of dirt to make it look > just as dirty as it was before. Yeah, right, Scott. > I suspect that the dealership actually did flush it, it's just that in > order to get the recovery tank, it needs to be removed, and they didn't > do that. It only takes a very small amount of dirt to make it look > just as dirty as it was before. How "clean it looks" probably isn't all that important. They could have used an OEM factory sealant, which might make it look brown and gunky even though it should function perfectly. Even a bit of grit shouldn't be too much of an issue. I always thought the most important function of a coolant change is to replenish the corrosion inhibitors. > > I suspect that the dealership actually did flush it, it's just that in > > order to get the recovery tank, it needs to be removed, and they didn't [quoted text clipped - 6 lines] > be too much of an issue. I always thought the most important function > of a coolant change is to replenish the corrosion inhibitors. I know lots of heater cores that would argue that point. The stirred up scale from a shoddy flush is a killer for heater core fluid flow. It blocks them up. If you have crap in the fluid, the engine block water jacket plug also needs to be removed for a proper flush That is usually a pipe thread fitting at the lower back somewhere. It is amazing how much crap can be stuck in the block. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's >>>I suspect that the dealership actually did flush it, it's just that in >>>order to get the recovery tank, it needs to be removed, and they didn't [quoted text clipped - 10 lines] > scale from a shoddy flush is a killer for heater core fluid flow. It > blocks them up. My main experience is with Japanese make cars using silicate-free coolants. The standard recommendation is to simply drain and refill the coolant even though maybe 70% of capacity is drained (including the engine block). I changed the coolant in my '95 Integra GS-R every 15K miles with just a drain and fill each time. There wasn't much stuff floating in there, and the radiator lasted until there was a crack in the plastic tank at 130K miles, which I hear isn't unusual. Honda only sells its current Type 2 extended-life coolant premixed with DI water. Flushing isn't a good idea with this premixed coolant because it won't be possible to get the concentration back up to 50/50, especially if you're flushing the block. > If you have crap in the fluid, the engine block water jacket plug also > needs to be removed for a proper flush That is usually a pipe thread > fitting at the lower back somewhere. It is amazing how much crap can be > stuck in the block. I never saw much crud (if any), but it could have been because I used distilled water every time (as recommended in the owner's manual). |
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