HAWAIISTANG66
Active member
what do you guys think is the best route/product in clearing engine block cooling passages?
best method for clearing cooling passages
- Thread starter HAWAIISTANG66
- Start date
shmoozo
Famous Member
HAWAIISTANG66":1eeqsy67 said:
It'll help us to know your situation in a bit more detail. To put it another way ...
Is the engine still in the car, fully assembled and operational?
- or -
Is the engine out of the car and stripped down to the bare engine block?
- or -
Is it something in between those two? If so, please specify.
The reason I ask is that methods for cleaning out the block's cooling passages will vary a bit depending on circumstances.
HAWAIISTANG66
Active member
no, it's in the car, i'm considering taking the head off and taking a pressure washer to the cooling passages....the car has been over heating, tried everything replaced the head a few years ago, came out of a car that didnt overheat at all....now still has an overheating problem....but to answer your question, everything is still together running.....just really hot i've let it get to 250 and just shut it down from there
I would normally say hydrochloric acid. You need to be excessively careful with this, as it can cause significant injury.
The strength sold for cleaning masonry and adjusting swimming pool pH is diluted about 20:1. First drain any antifreze and rinse well internally (cold motor), then determine the volume of water your cooling system holds by filling and burping it, one pint at a time. Drain 1/20 this amount, and make it up with acid.
Now run the motor until hot and the thermostat is fully open. Let it cool and repeat. Now when it's only warm to touch, carefully "crack" the lower radiator hose and drain with a funnel and bucket.
Once the flow is only a drip, carefully remove the radiator, hold upside down with top hose removed (cap still on) and flush clean with copious amounts of water - then remove the cap and flush some more. Rinse any splashes onto the bodywork immediately.
Now remove the thermostat housing, and if possible the block drain plug. Blast away with the regular hose (not pressure washer) through the head, to reverse flush all the sediment that's been loosened, again taking care not to allow contaminated water/sludge to remain on the body. After a bit you might even pull off the water pump to see how much more can be flushed out...
Depending on how crudded-up the block is, you might want to repeat the whole process, or even try it again with 1/10 of the cooling water replaced by acid. The main thing would be not to leave it full of acid for a week! At the completion of all flushing, buy or improvise an uper hose filter and expect to change the coolant within a fortnight as it neutralises residual acid and loosens more rubbish.
The strength sold for cleaning masonry and adjusting swimming pool pH is diluted about 20:1. First drain any antifreze and rinse well internally (cold motor), then determine the volume of water your cooling system holds by filling and burping it, one pint at a time. Drain 1/20 this amount, and make it up with acid.
Now run the motor until hot and the thermostat is fully open. Let it cool and repeat. Now when it's only warm to touch, carefully "crack" the lower radiator hose and drain with a funnel and bucket.
Once the flow is only a drip, carefully remove the radiator, hold upside down with top hose removed (cap still on) and flush clean with copious amounts of water - then remove the cap and flush some more. Rinse any splashes onto the bodywork immediately.
Now remove the thermostat housing, and if possible the block drain plug. Blast away with the regular hose (not pressure washer) through the head, to reverse flush all the sediment that's been loosened, again taking care not to allow contaminated water/sludge to remain on the body. After a bit you might even pull off the water pump to see how much more can be flushed out...
Depending on how crudded-up the block is, you might want to repeat the whole process, or even try it again with 1/10 of the cooling water replaced by acid. The main thing would be not to leave it full of acid for a week! At the completion of all flushing, buy or improvise an uper hose filter and expect to change the coolant within a fortnight as it neutralises residual acid and loosens more rubbish.
HAWAIISTANG66
Active member
would you find that at home depot ?
8) yes you can find it at home depot. look in the pool supplies section. have you checked the flow through the radiator? are the cool spots on the radiator with the engine warmed up? have you back flushed the engine? what color is the coolant in the engine?
most of the time cooling system problems are focused on the radiator. after that you have problems with too much or not enough ignition timing, lean fuel mixtures, air flow not gettong out of the engine compartment, hot air flowing out the engine compartment under the radiator and then flowing back through the radiator.
check the radiator before you start putting acid in the system to clean out the passages. and dont forget that if you do use acid, you must keep a close eye on your seals afterwards since acid will eat at the rubber seals in the water pump, and other places.
most of the time cooling system problems are focused on the radiator. after that you have problems with too much or not enough ignition timing, lean fuel mixtures, air flow not gettong out of the engine compartment, hot air flowing out the engine compartment under the radiator and then flowing back through the radiator.
check the radiator before you start putting acid in the system to clean out the passages. and dont forget that if you do use acid, you must keep a close eye on your seals afterwards since acid will eat at the rubber seals in the water pump, and other places.
66 Fastback
Famous Member
Although it would not hurt to clean the block, I believe your problem lies with the radiator or the ignition timing as rbohm mentioned. You engine is running hot because you cannot reject enough heat through the radiator or your engine is generating too much heat. Fouled engine coolant passages would reduce the amount of heat transfer into the coolant. Replacing the radiator would be a more effective approach. However, before you do that, check the ignition timing. Make sure the balancer's timing mark has not slipped and the engine is at TDC when the balancer indicates it is at TDC. Make sure the vacuum advance is functioning. Do you have the stock Load-a-matic distributor and the stock carburetor? Retarded timing will cause an overheating problem. As previously mentioned also look for indications of a lean mixture that could be causing it to run hot.
Doug
Doug
HAWAIISTANG66
Active member
I dont have the stock distributor. It's the DSII in it, I've had that in there for a few years, but I do have the stock carburator.
I also replaced the radiator just to make sure it wasnt the problem, I actually did that twice, My dad did that when i was away for 5 years in the Marine Corps and left the car back in MS while i was gone. Then I replaced it again with a 3 core a couple months back just to make sure, and it still overheats, I get the cooling passages theory from the fact it was sitting up for 5 years, and the coolant does flow through the radiator you can see it after the thermostat opens.
Just to add to this I do have a newer a/c system in it with 2 electric blowing fans and a 5 blade flex sucking fan with shroud......I wired the two electric fans to stay on with the a/c off....doesnt help....so....you can see where I'm trying the extremes
oh and the coolant looks fine.....nice and green
I also replaced the radiator just to make sure it wasnt the problem, I actually did that twice, My dad did that when i was away for 5 years in the Marine Corps and left the car back in MS while i was gone. Then I replaced it again with a 3 core a couple months back just to make sure, and it still overheats, I get the cooling passages theory from the fact it was sitting up for 5 years, and the coolant does flow through the radiator you can see it after the thermostat opens.
Just to add to this I do have a newer a/c system in it with 2 electric blowing fans and a 5 blade flex sucking fan with shroud......I wired the two electric fans to stay on with the a/c off....doesnt help....so....you can see where I'm trying the extremes
oh and the coolant looks fine.....nice and green
66 Fastback
Famous Member
I would start wondering about the timing, slipped harmonic balancer, and or the lean condition if you have a over-heating problem with a new radiator. What symptoms of over-heating are you fighting? Are you physically boiling over? Or do you just have a temperature gauge that is reading high?
Gauges and Temp senders are notoriously inaccurate.
Boiling over could also be caused by a bad radiator cap.
Doug
Gauges and Temp senders are notoriously inaccurate.
Boiling over could also be caused by a bad radiator cap.
Doug
This is maybe the first time I've ever disagreed with you, Doug.
But I believe that the block can cause heat problems, in addition to those other causes you cite. Cleaning out the block can't really hurt; the acid will attack iron oxide much more readily than "pure" cast iron.
• Another heat issue I have experienced myself on the DD is overheating due to ring/bore wear. As the rings no longer transfer heat effectively to the bore and the PCV is substantially crippled (blowby), the whole mass of engine gets hotter, and stays hotter. Only a long drive in cool conditions will bring it back down - this is after flushing the cooling system as described above, and verifying all thermo/vacuum devices work. I mention this because it's interesting and outside the usual scope of consideration.
Regards, Adam.
But I believe that the block can cause heat problems, in addition to those other causes you cite. Cleaning out the block can't really hurt; the acid will attack iron oxide much more readily than "pure" cast iron.
• Another heat issue I have experienced myself on the DD is overheating due to ring/bore wear. As the rings no longer transfer heat effectively to the bore and the PCV is substantially crippled (blowby), the whole mass of engine gets hotter, and stays hotter. Only a long drive in cool conditions will bring it back down - this is after flushing the cooling system as described above, and verifying all thermo/vacuum devices work. I mention this because it's interesting and outside the usual scope of consideration.
Regards, Adam.
66 Fastback
Famous Member
I don't diasagree that cleaning the block would help. I have cleaned it with acid myself. Although at the time I figured that if a little was good more would be better. I ran the engine with the radiator cap on and when she hit operating temp, I thought something was going to blow. It was jetting all it could out of the radiator cap relief valve. The hose was bucking. What is it they say, something like so many degrees of temp increase doubles the reaction rate.
Anyway, I guess it depends on what he is calling "overheating". Is it symptons at the radiator such as boiling over? High indicated coolant temp? Or detonation from high temps? What I am saying, is if the engine block cooling passages are fouled, the heat will not transfer into the coolant as well. That would be a worse condition for the engine. The block temp would be high because it is not able to reject its heat into the coolant. Fortunately, thermodynamics have a way of compensating for this. As the block temp increases, there would be a higher temperature differential that would act as a higher driving force to drive the heat through the fouled coolant walls and into the coolant. If the radiator side of the system is working properly, then it should be able to reject the heat. The fouled tubes are not going to cause any additional heat to be generated in the coolant unless the block is overheating to such an extreme that tolerances are reduced and more friction is created.
If he is chasing symptons at the radiator side of the equation, such as coolant overflow, then he might be dealing with a problem of rejecting the heat into the air.
But as mentioned, it is possible that a normal functioning cooling system is being overloaded due to improper timing, lean fuel mixture, or high friction loads as you mentioned.
Doug
Anyway, I guess it depends on what he is calling "overheating". Is it symptons at the radiator such as boiling over? High indicated coolant temp? Or detonation from high temps? What I am saying, is if the engine block cooling passages are fouled, the heat will not transfer into the coolant as well. That would be a worse condition for the engine. The block temp would be high because it is not able to reject its heat into the coolant. Fortunately, thermodynamics have a way of compensating for this. As the block temp increases, there would be a higher temperature differential that would act as a higher driving force to drive the heat through the fouled coolant walls and into the coolant. If the radiator side of the system is working properly, then it should be able to reject the heat. The fouled tubes are not going to cause any additional heat to be generated in the coolant unless the block is overheating to such an extreme that tolerances are reduced and more friction is created.
If he is chasing symptons at the radiator side of the equation, such as coolant overflow, then he might be dealing with a problem of rejecting the heat into the air.
But as mentioned, it is possible that a normal functioning cooling system is being overloaded due to improper timing, lean fuel mixture, or high friction loads as you mentioned.
Doug
HAWAIISTANG66
Active member
as far as the symptoms, it's mainly the temperature. I currently have the stock temp sensor on the car as well as an aftermarket and stock sensor and gauge running to the thermostat housing that's where I've gotten the 250degrees from. I've never had it boil on me, only get really hot on the aftermarket temp sensor, the same temp sensor was used on the donor car that the head is from with no high readings, it just baffles me that these cars from over 40 years ago didnt have 3 core radiators, electric fans or 5 blade flex fans and had to have ran cool off the dealer floor. just to add, I bought this short block about 7 years ago 5 of which as i mentioned earlier was sitting in an open garage inside the car.
Oh I've messed around with the fuel mixture, basically all i can do is get the car to run smoothly at idle, that's all I know to do, I think I have a timing light, but usually I do the same with the distributor a smooth sounding engine instead of using the timing light. I know this probably isnt the prefered method, but I figure if it runs smoothly how could it be wrong? It's funny as an aircraft mechanic, I'd never do that working on an airbus or such, everything is precision. but i guess i still have some shadetree in me
Oh I've messed around with the fuel mixture, basically all i can do is get the car to run smoothly at idle, that's all I know to do, I think I have a timing light, but usually I do the same with the distributor a smooth sounding engine instead of using the timing light. I know this probably isnt the prefered method, but I figure if it runs smoothly how could it be wrong? It's funny as an aircraft mechanic, I'd never do that working on an airbus or such, everything is precision. but i guess i still have some shadetree in me
8) when was the last time you replaced the thermostat? whne you swapped heads, did you check the head surface and block deck for damage or warpage? also when you had the head off the block, did the passages look partially plugged? was the coolant then looking rather rust colored? have you checked the exhaust system for restrictions? how good are the hoses on the car? how good is the radiator cap on the car?
66 Fastback
Famous Member
I think you could have a timing issue. Two things come to mind.
You mention you have the DS II distributor and the stock carb. Where is your vacuum line to the distributor connected? If you connect the vac line to the stock carb, it will not provide proper vacuum advance. You might try a manifold vaccum source.
I would also check the position of the timing mark on the balancer relative to the actual TDC of the #1 piston. My car had a slipped harmonic balancer ring, so I was timing it by ear because it would not run correctly if I timed it with the timing light because the index mark was off. Once I got the carb / distributor issues and replaced the harmonic balancer,, my overheating issures dissappeared.
Doug
You mention you have the DS II distributor and the stock carb. Where is your vacuum line to the distributor connected? If you connect the vac line to the stock carb, it will not provide proper vacuum advance. You might try a manifold vaccum source.
I would also check the position of the timing mark on the balancer relative to the actual TDC of the #1 piston. My car had a slipped harmonic balancer ring, so I was timing it by ear because it would not run correctly if I timed it with the timing light because the index mark was off. Once I got the carb / distributor issues and replaced the harmonic balancer,, my overheating issures dissappeared.
Doug
Hi Hawaiistang66.IIRC muratic acid does`nt like ALUMINUM.It will eat it like you eat M&M`s(R).Hehehehehe.Leo
HAWAIISTANG66
Active member
ADD VACUUM AND IT SHALL COOL!
"T"ed the vacuum line that goes to the brake booster into the DSII and it as soon as it was hooked up it seemed like a load was taken off of the engine, I turned the a/c on w/o the electric fans just to get it warmed up to see where it would climb to and it wouldnt go past 180 drove it down the road and the same stands wouldnt go past 180, but now i have to replace the starter....fix one thing and another arises
i didnt think such a small thing woudl make such a difference.....
thanks to all i'm glad i didnt have to flush anything
"T"ed the vacuum line that goes to the brake booster into the DSII and it as soon as it was hooked up it seemed like a load was taken off of the engine, I turned the a/c on w/o the electric fans just to get it warmed up to see where it would climb to and it wouldnt go past 180 drove it down the road and the same stands wouldnt go past 180, but now i have to replace the starter....fix one thing and another arises
i didnt think such a small thing woudl make such a difference.....
thanks to all i'm glad i didnt have to flush anything
66 Fastback
Famous Member
Glad to hear you solved it. Many folks don't realize how much retarded timing affects the temperature. When mapping the advance curve on an engine, I'll disconnect the vacuum advance and it does not take long for the temperature to climb. Over-advanced timing does not increase the temp like retarded timing, but the advanced timing leads to pinging.
Doug
Doug
