4.2 coolant flushing, do I need to remove thermost - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 11-09-2002, 12:58 PM
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4.2 coolant flushing, do I need to remove thermost

I have warmed up motor, drained, filled with flush and water, run for 10 mins, drained, and now run with straight water for 10 mins.

I still want to just flush out the block, but figure it will be mostly just sediment and crap, not coolant that will run out onto the ground.

Whcih radiator hose do I want to put my garden hose into, top or bottom?

I'd assume top, but won't the thermostat close because of the cold water and stop the system from flushing?

Do I need to remove the thermostat and reinstall the cover and flush? I already have a new 195 degree thermostat and gasket to install, so I will need to pull the old one at some point anyhow.

Thanks,

Mike
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post #2 of (permalink) Old 11-09-2002, 02:14 PM
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flushing method worked>>

For those that care, removing the thermostat, reinstalling the tthermostat cover and using a garden hose into the upper radiator hose with the lower disconnected seems to work well to flush the system.

Not sure how much of teh block I am actually flushing, but I did get the water to run clear(as opposed to the nice rust color it was) after a few gallons.

DO NOT try this on a hot engine or you risk damaging something, like cracking a head or block, let the engine cool down first.

Mike
post #3 of (permalink) Old 11-09-2002, 04:04 PM
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Re: 4.2 coolant flushing, do I need to remove thermost

Here's what I do:

1. Throw some chemical (prestone, etc.) for the "flush'n fill.
2. Heat up engine to get the chemical mixed.
3. Let the engine cool.
4. Remove the top radiator hose.
5. Remove the thermostat (avoids debris catching or fouling).
6. Install the water in the radiator.
7. Reinstall the upper hose bib on the engine (minus the thermostat).
8. Reinstall the upper hose on the bib.
9. Point that hose out of the radiato toward something needing watering.
10. Put a garden hose in the radiator with a on/off valve on the hose at the output of the hose.
11. Start the engine (Carefull because water will spray!).
12. Start pumping in and out the water till the water runs clear from the upper hose..
13. Reinstall everything.
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post #4 of (permalink) Old 11-09-2002, 04:25 PM
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couple questions>>

Leve, a couple questions.

First, will a garden hose provide enough flow for the pump?

Second, will the pump be destroyed if it runs out of water for lubrication, even momentarily?(I've destroyed a pump on an outboard that way).

Third, the pump draws water from the bottom of the radiator, correct?

Finally, I made an adapter from a large socket that was a tight fit inot the upper hose. Then I put a piece of fuel line thru the square hole in the socket and used duct tape to seal it up. I plan on using my compressed air tank to blow all the water out of the block/heater core/manifold, and figure I can get more of the water out under pressure than just by draining from the lower hose.

Is this a good idea? Will it help? Maybe more importantly, will it hurt anything, i.e., anything that will be hurt by 20+ lbs of pressure on it?

thanks,

Mike
post #5 of (permalink) Old 11-09-2002, 04:31 PM
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Re: couple questions>>

</font><blockquote><font class="small">In reply to:</font><hr />
First, will a garden hose provide enough flow for the pump?

[/ QUOTE ] Yes
</font><blockquote><font class="small">In reply to:</font><hr />
Second, will the pump be destroyed if it runs out of water for lubrication, even momentarily?

[/ QUOTE ]No, but keep the water flowing! </font><blockquote><font class="small">In reply to:</font><hr />
Third, the pump draws water from the bottom of the radiator, correct?


[/ QUOTE ] Yes
</font><blockquote><font class="small">In reply to:</font><hr />
Is this a good idea? Will it help? Maybe more importantly, will it hurt anything, i.e., anything that will be hurt by 20+ lbs of pressure on it?

[/ QUOTE ]Is it a good idea? Well, I don't think it's good or bad...if the chemical hasn't removed the scale it's not going to flush out under air pressure. I feel that this step is not necessary.

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post #6 of (permalink) Old 11-10-2002, 07:27 AM
 
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Re: couple questions>>

</font><blockquote><font class="small">In reply to:</font><hr />
Second, will the pump be destroyed if it runs out of water for lubrication, even momentarily?(I've destroyed a pump on an outboard that way).

[/ QUOTE ]

Just for your information a outboard or a inboards (seawater) water pump has a rubber impeller that turns inside of a brass or stainless steel housing the rubber blades of the impeller touches the housing as it turns. The water is what lubes and cools the pump. That is why dry running them even for a few seconds will damage them. The rubber melts and the blades stick and get torn off. I always loved the guys who would say my boats not pumping water then you ask them if they dry ran it and they would say "Oh no!" then you pull the pump and it a blob of rubber and then they say "It must have been those dang kids!" [img]images/graemlins/smile.gif[/img] You'd be surprised to hear of all the things those dang kids get blamed for!

A automotive style water pump has a steel impeller that is close to the housing but it doesn't touch so dry running them won't hurt them but will overheat the engine.

One other thing if you can get to the block drain plug easy it helps to get more sediment out if you pull it out and flush without the engine running.
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post #7 of (permalink) Old 11-10-2002, 08:52 AM
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boat water pump>

Hey, thanks for the reply.

Yeah, I know all about the outboard motor pumps, lol. My motor wouldn't run right and we rebuilt the carb and it wouldn't run right at the marina. The ramp to the water was at about 45 degrees(barely an exageration) and the boat wasn't that much lighter than my Jeep which I was pulling it with. Combined with an emergency brake that is barely adequate and tires slipping on the slime covered boat ramp as the Jeep gets pulled down the ramp backwards into the water makes for an entertaining experience to say the least.

I figured I'd be "smart" and test the engine on land after a few scares on the ramp instead of submerging the Jeep. We got the engine running for about 5 seconds(out of water) and a lovely burning smell accompanied by smoke comming from the exhaust port was the result.

I had to pull the bottom of the motor off to replace the pump, I hadn't realized they were rubber impellers or wouldn't have tried that, lol.

I know a car pump isn't like that, but I was wondering if it needed water to lube it's bearings or something.

What also sucked was that the marina mechanic(old redneck guy with no teeth and 2 cigarettes hanging out of his mouth) watched us try to start the motor a couple times out of water and watched us run it out of water. Sorry bastard could have given us a shout to warn us...... I think he was just hoping I'd pay him to fix it when I destroyed the pump. I hate ppl like that.

Mike
post #8 of (permalink) Old 11-10-2002, 09:34 AM
 
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Re: boat water pump>

Yep, He was seeing easy $$$ in replacing the pump. I don't care for people like that either but unfortunity there are lots like that. In my experiance (15+ years as a auto and marine mechanic) most are shop owners some not all! I on the other am not like that and I have been talked to before by a couple bosses saying I was giving the customer "To Much Info" that I should just say "bring it in and we'll take a look at it" but my thinking is if you help a guy out and save him a few $$ doing something simple when he needs something done he can't do who do you think he'll bring it to?

But hey, not everyone thinks like I do and plus I quit getting interupted to talk on the phone as much after that.When I did I would just watch what I said on the phone when the boss could hear [img]images/graemlins/wink.gif[/img]

I guess some people don't understand there is more to life then just money but then they probably never owned a Jeep! [img]images/graemlins/smile.gif[/img]
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