cutlass47

My 72 Cutlass with 350 ci engine has 192,000 miles- had car since new. I am gradually replacing parts and fluids. Today I put on new radiator and heater hoses (last done about 20 years ago when I put a new 3 core Harrison radiator in, but car has only been driven about 1,000 miles in last 20 years and 250 since 11/06) and sat in my garage for about 3 years without water/coolant in the radiator. About 2 yrs. ago I got it running again and had engine power flushed and new coolant put in. When I drained the radiator and changed the hoses today, I was surprised at how clean and dark green the water/coolant was, however, there was a great deal of white sediment on the fins inside. I decided to put some Prestone Radiator Flush in radiator to hopefully clean the inside fins, but it looked no cleaner afterwards. Would it be worthwhile to try the stronger Prestone radiator cleaner before I put in new coolant (which I should have tried first anyway) or not waste my time and just take the radiator to radiator shop and have them clean it?
Also, what is the correct or factory thermostat for this engine - 180 or 195 degrees? It has a 195 degree T-stat in it now and no overheating problems in the past that I am aware of, such as radiator boiling over (car only has idiot lights, no oil pressure or water temp gauges). Again, I have just driven it for short distances and not on freeway, so no real test of system in last 2 1/2 yrs.

Wasted

I took my 40+ year old radiator in to a shop and it came out looking brand new. So If I was you I just wouldn't waste the time flushing it. About the thermo I have a 180 but I don't know if its stock.

Olds64

If your radiator needs to be repaired then it is better to take it to a shop or replace it. Flushing a radiator just makes sure the coolant in it is fresh and won't cause corrosion. I am not sure what T stat your car needs. If the one you have works then keep it.

Lady72nRob71

The flush stuff is not too useful. Did you use two bottles for that big cooling system? Even still, it will not clean much

I used the Prestone HD cleaner, two bottles as recommended. Same chemical as the flush but more comes in a bottle... It is sodium nitrate, a food additive! Therefore I did not recover it for recycling.
Make sure all coolant is out (drain the block with the 2-3 plugs on the sides). Flush with water a few times. Add cleaner and water.
Drive a minimum of 6 hours - go for an all day drive!
Let engine cool (or wait til next day & run just enough to get it warm) then drain it and flush the block, radiator, and heater core with a hose.
Fill with water, run 5 minutes with radiator cap off, and drain. Repeat until no more foamy residue can be seen in radiator.
Fill with 50/50 distilled water and good coolant.

This cleaned my radiator well, but not as good if a radiator shop does it off the car. The highly-acidic chemicals they use would not be suitable for your block and water pump...
Weigh the costs-vs-results on doing both. If your old radiator has any corroded areas at all, have a shop clean it and fix any leaks that could have caused the corrosion. They will pressure test also. The radiators on these big cars are easy to pull.

I use only the Mr Gasket high-flow 180 t-stats in my cars, though 192 or 195 was stock from the factory...

Cecil Anderson

Could someone tell me the proper way to flush the engine block. 75 Cutlass colonade 350 4bbl. Sat for a long time. Runs great but water looked like rust radiator came clean by running clean water thru it Andy

Lady72nRob71

Not sure if there is a 'proper way' but I came up with my own way...

Best way I found is to force water in (with a garden hose) through both the rear heater outlet at the back of the intake manifold and through the front top water outlet (remove T-stat first), but do them independently. Block the lower radiator hose outlet first for all cases. Pull the block plugs for outlets (2 or 3 of them on the sides of the block above the oil pan.) I alternaternated water flow combinations like heater outlet to LH block plugs, then front water outlet to RH block plugs, repaeated those two with all block plugs pulled, then even ran heater outlet to front water neck with the block plugs installed and vice versa... What you want to do is stir up sediment and flush it out. When water looks clear, do a clean and flush as i mentioned in the post above. This should get it pretty clean... Luckily, all this is only needed if there is significant deposits in the block from sitting too long, using water instead of coolant, etc.

Some good news is that the heater valve is normally open. Applying vacuum closes the valve. (On all my cars at least...)

cutlass47

I have just finished flushing the coolant in my 72 Cutlass, and I decided to change the thermostat and old short hose and clamps on the housing to water pump. What is easiest way to reinstall short hose and thermostat housing and do I put any gasket sealant on Felpro cardboard gasket and if so on both sides or which side or just put t-stat on dry? I have cleaned surfaces of housing and manifold and want to make sure I have a good seal.

I do not know if the best and easiest way is to attach the short hose to the pump first and then work the curved pipe into the attached hose and then put the housing in place or put the housing on first and then attach the hose and clamps.

Thanks for you help

Lady72nRob71

Well, I did two of these last summer - heres what I did.
I had the felpro self-adhesive gaskets and Mr Gasket high flow 180 t-stats...

Blow out holes for water outlet bolts...
Scraped off all old sealer and gasket crap with razor blades, avoiding damage to intake.
Cleaned & scaped water outlet housing and sanded it lightly on a known straight surface with fresh 600 grit wet / dry paper.
Washed again and cleaned sealing surfaces with rubbing alcohol.

Cut bypass hose same length as old one, installed on water pump with clamp, put second clamp on top of that loosely. Rubbed a very little fresh coolant inside the top of that hose to lubricate it.

Correctly placed thermostat on recession in intake and verified it was pointing the right way (spring side or copper rod down).

Pulled white paper from gasket. Carefully stuck sticky side of new gasket to intake, lining up screws holes first. This "captured" the thermostat.
Placed bolts, socket, and ratchet within easy reach.
(If you have the non-self adhesive gaskets, then put sealer on this side the same as the one described below.)

Applied thin layers of Permatex #2 gasket sealer to upper non-sticky side of new gasket and water outlet, waited until just tacky (like instructions say.)

Twisted housing onto bypass hose while pushing down hard and cursing the hose... Try not to disturb gasket and sealer. If you do a little, it should still be okay (I did this before several times).
When it was almost home I pushed down HARD, lined up the bolt holes, cursed more, got the bolts started and ran them in with a socket and extention by hand. When down snug, used rachet and alternated between bolts. Torqued to (I thinK) 15 ft lbs. (Consult your manual).
If you feel bolt start to strip, stop and curse more! If over 10 Lbs, leave it and see if it leaks - it may be okay, but helicoils will be in the future... Dont ask how I learned this part...

Position and tighten the upper bypass hose.
Sounds like overkill, but I have yet had one to leak on me...

88 coupe

195°.

If that is where it is running, relax and enjoy the drive.

Norm

cutlass47

Thanks to all for the feedback. Rob, I was running out of daylight yesterday and weather was predicted to get rainy and cold today, so I proceeded reinstalling t-stat housing before I received your good instructions. I put the housing back on with just putting permatex sealer on housing side of gasket and not on the intake side, as you suggested to keep the t-stat in place. Now I am concerned that I might not have gotten t-stat postioned correctly in the intake hole. The bolts seemed to go in alright and there was no leakage last night. When I had put new coolant in radiator and engine ran for about 10 minutes without radiator cap on, coolant started bubbling up and ran out of the top and I quickly put cap back on. (1)Would this have been a problem with the Robertshaw 95 degree t-stat or was air in system causing this overflow? (2) How will I know if there is still air in the system? I plan to put the rest of gallon of coolant in this morning -so far I was able to get 1 3/4 gallons of new coolant back into system after draining as much of old coolant and one bottle of Prestone cleaner with one draining from petcock. I did not use water hose to get old coolant out of block or remove the bolts on side of engine to drain coolant, as you have suggested, but the coolant coming out in initial and drain was remarkably clean and dark green (car only driven about 250 miles since old coolant put in after power flush in 11/06). I did use water hose to wash out the heater core before I put new heater hoses on.
(3)Should I just finish filling up with distilled water or see if I can get the rest of the gallon of coolant into system to acheive a 50 -70 % mixture--since I did not get all of the old coolant out in intial drain and second drain thru petcock after putting in Prestone cleaner? Sorry about all of the detail. Thanks for your input. Tommy

Lady72nRob71

Tommy,
If you got the T-stat in wrong, leakage would probably occure. The big thing is that you got the spring or copper rod side of the t-stat down in the intake hole. If it is upside down, the car would overheat in no time. Was your heater turned on to purge the air from the heater core?

The overflow prolly occured when the t-stat opened, sending a big air bubble into an almost full radiator, making it overflow. I have seen this in the past if you fill it too full while the engine was stopped. The air will eventually reach the top of the radiator, so just run the car until hot (just drive local distances) and check the level the next morning when the engine is cool. Add as needed Do that a few times until you have to add no more. Be sure your overflow bottle is full of fresh coolant.

Last year when I did my two Olds, (after draining the block), I filled the radiator to 3/4 full with 50/50 with engine stopped, started engine, turned heater on, and then level imediately dropped (air is purged). with engine running, I added more coolant and distilled water until I got to 3/4 full. Ran until t-stat starts to open. At that time you can actually see the coolant pushing through the internal radiator tubes. I filled slowly with half coolant and distilled water until I reached the top of the radiator neck. No additional burping was needed and there was no spillage. After so many years, i finally got the procedure optimized...

Now since you did not drain the block, you may only be able to get 2.5 to 3 gallons tops into it, as the block holds 1 to 1.5 gallons...
Try to judge the amount of coolant and amount of distilled water you added to try to make 70% coolant mixture, as the stuff in the block was watered down from your previous flush.

Hope this helps...

As easy as the block drains are to get to on the Olds engines, I would always recommend pulling them when flushing or cleaning. Hardest part might be finding them under any accumulated grime the 1st time...

mugzilla

has any one heard of using 20 mule team borax ..?