I want to do a flush and fill on the cooling system.

I read through the FAQ link here: http://web.archive.org/web/200806181...ca/mvp.php/502

The guy makes it sound like removing the block drains is difficult and maybe risky. True? False? I don't know if these drains have been out in 125K miles and 20 years, or not. I need a low risk approach as the car must be ready to roll long distances in a few days with no worries, so I am thinking of a water flush and then filling with full strength coolant of the proper amount, then topping with water.

Am I right that coolant or flush water won't flow through the blow unless I get it hot enough to open the thermostat? Can I flush with a hose through the radiator hose to force flush the block?

Ideas appreciated!

 

Getting to the drain plugs in the block is difficult. Removing the drain plugs is the best way to flush, though. If the engine is cold, the thermostat will be closed and prevents the block from draining. Even if it is open, or you have removed it, it is located higher in the block than the drain plugs and you still won't get all the water to drain out.

The drain plugs should not be a problem even after 20 years, but they might be tighter because of 20 years. If you are going to remove the drain plugs, I highly recommend a 6 point socket to avoid stripping the head of the plug.

A more time consuming way to flush the engine would be after the flush chemicals, fill the engine with plain water and run it until the thermostat opens and circulates the water. Then stop the engine and drain it. You will have to do this several times until the water drains out clear. Then you can add the fresh anti-freeze.

You could also run the engine without the radiator cap off and when the thermostat opens, open the drain and put a hose in the radiator and run the water, but not full blast, try to match the rate of water draining out. The cold water will probably cause the thermostat to close, so you will have to turn off the hose and close the drain and wait for the engine to heat up again. Removing the thermostat would allow you to do this type of operation quicker.

 

Thermostat removal looked slightly involved... as in an hour or more to remove the belt, get to unit, etc.

Is is easier/faster than it looks?

 

It is not difficult, but it will take longer than an hour. The car will need to be raised in the front to bleed the air out.

The engine drain plugs are difficult to reach. I had no luck with them. I drained coolant by opening the valve at the bottom of the radiator. You could run the car while a garden hose adds water as fast as the valve drains it. Then remove the hose, turn the car off, then let it drain. c lose valve on radiator. Add full strength antifreeze.

Check your coolant with a gauge to make sure it is strong enough for expected winter temperatures.

 

Is that true no matter what? Even if I do the drain, water fill, run to hot, cool, drain, water fill, run to hot?

Is there a bleeder, or does it just flow to the high point?

 

There is no bleeder on the engine, that's why it is recommended to raise the front end. As everyone knows, air always goes to the high point. With the car sitting on level ground, there isn't really a high point that will let the air out.

 

The Lisle coolant funnel is awesome! It makes coolant flushes so easy!

 

Sounds good. Thanks.

 

Based on your skill level OP, going the drain plugs route isn't going to be your cup of tea. Just drain, fill, and bleed air from the radiator.

When bleeding air, you should have your heater on, and set to the max speed.

Raise front of car too as mentioned.

I use the Lisle funnel too, eliminates most of the spillage/bubbling over.

 

Well, I have the skills... it's the unfamiliarity with this car and a "must be done" time frame that is making me cautious. I have no room for error time-wise i.e. "hey, I broke something and now I need to wait a week while it ships in" and/or "spend six hours fixing something I didn't expect to work on".

So much to do, so little time.

 

The Wizard must share the same opinion. The engine drain plugs are difficult to access, and a pita.

That is why we do things the hard way, because it is actually easier.

 

Wizard... regarding the simple drain and fill approach, I always let the engine run with the heater on hot and high fan like you say, but to let the air bleed out, I leave the radiator cap off till the radiator fans come on a few times. Then I shut things down and once things have cooled down a bit, I put the radiator cap back on. Good approach for the air bleed? I've never raised the front end for the job and it seems to work pretty well.

I do it frequently enough that I don't worry about getting out all the coolant from the block by not removing the plugs. I also always use the genuine Nissan Long Life Coolant and distilled water.

 

Yup, that's a solid approach and how I do it. Add in the Lisle funnel, and there's no mess.

 

After a peek, the thermostat wasn't at all hard to reach. Haynes made it sound inaccessible. But, since time was short and there was no room for risk (car had to head out on a trip with no time for a snapped stud or possibly a run to the junk yard to replace a housing with a corroded face), I decided to leave the thermostat in for this round.

Instead I did a back-flush with the garden hose.

First, drained coolant out the bottom of the radiator. Filled with hose water, ran to hot, let cool, drained again. Pulled upper radiator hose from the engine and stuck the garden hose in the engine coupling. Turned the water on hard and let it flow. I got non-clear water coming out for about ten minutes as it went in and out (same opening, but it worked well).

Once clear I drained again and filled with distilled water. Ran to hot, let cool, drained again. Drained the radiator hoses. At that point I figured it was mostly distilled water left in the block with maybe a small amount of hose water (good quality water around here). Closed up, filled with a gallon of Pentosin A2 (Asian), then topped with distilled.

Jacked front end high, warmed up, vented air out the radiator. Closed up and topped off a couple days in a row when cold.

 

Sounds like you were successful.

Congratulations.

 

I'm not good doing block drain. I do rad drain and fill every three years, bleed by jacking up front end. I don't have the Lisle tool, I use an old CV boot that fits in the rad opening. Lol
After nearly 20 years I'm going to do thermostat soon, pushing my luck.

 

ha, i've had the original thermostat in my almost 22 y/o max since day one. i had a garage drain and fill the front 4 or 5 quarts of anti-freeze like 3 years ago, gonna do that again next week.

 

Thought I'd throw something else out here... if you do pull the thermostat, you can use a shop vac to suck most of the coolant out of the engine through the upper hose port without opening the block drains. How well it works depends on the internal passage design, but it works on most engines. If I had had the time to follow through on the thermostat that was my plan.

 

Original thermostat here as well (251k miles). Only work I ever had to do on my cooling system was new radiator last year.

 

If a guy has the $$$ and access to an air compressor, an Airlift is the bee's knees for evacuating air out of the system and refilling with coolant. The Lisle funnel is also a great tool. My original t-stat went well past 300K, I only changed it at that point as a preventative measure lol. Man I love these cars.