Cleaning water jackets 225

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williaml

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Long story but here is the condensed version. The car had the original engine when found in a barn. The owner got the engine to run but he said it kept overheating. He switched the engine out for a 1969 engine. I buy the car and want it to be as original as possible so when I purchased the car I had the original 1965 engine rebuilt. Once installed I noticed the engine would run hot by the gauge. It would pin all the way to the right. Then it will back off but never in normal range. I have ordered a auxiliary temp gauge and temp gun but if I need to clean water jackets while the engine is in the car what is the best way to do such. Has anyone got any ideas?

Thanks for reading
 
i wonder if a good flush of CLR would do it? drain and rinse out the whole waterjacket via the rad hoses, and then set up a pump to circulate CLR though the block for a while. have to remove thermostat as well.

i have no idea if this would wreck anything, so try at your own risk
 
Music acid works good. Fill the water jackets with acid and let it sir for several hours. Flush with water. Blow dry and repeat as necessary.
 
Blue Devil. Follow the instructions.
 
If the engine was rebuilt, wasn't the block cleaned? First thing would be to verify that it is really over heating. Might be just a gauge or instrument voltage regulator problem.
 
If the engine was rebuilt, wasn't the block cleaned? First thing would be to verify that it is really over heating. Might be just a gauge or instrument voltage regulator problem.

did the 69 engine overheat as well?

if not, swap the temp sending unit

if so, my moneys would be on a clogged up radiator
 
sediment in fluids... Shape of container, how much you stir it, what chemical(s) you add doesn't matter. Sediment will always collect at the lowest point. So if you really need to, Remove rear freeze plugs and go at it with a garden hose and spray nozzle.
 
No the 69 engine never ran hot. I had the radiator serviced and the tech said working fine as it should be
 
I doubt a rebuilder would not first hot-tank the block. Anyway, for in-car cleanup I bought citric acid on ebay. Mix ~1 lb per gal and drive for a day or 2. But first, totally flush out all coolant to pure water and again aftewards. I think the same stuff was in the better Prestone flush which you can't seem to buy anymore. Be careful using vinegar since one guy reported it attacked the cast iron when he left a head soaking in it for a week. Also, pull the block drain for the final flush (passenger side, 3/8" NPT plug) and dig any rust gunk so it free flows.

I have done this before switching to Evans Waterless Coolant, but you must totally dry out the innards, so need time, and best to do during a heater core and/or radiator swap.
 
Before going any further:

If the '69 never showed overheating.... did you take the temp sensor out of the '69 and put it in the '65 ? If not, then the '65 has a different temp sensor and THAT needs to be checked out first thing. There are a LOT of temp sensors that look the same but have totally different sensor resistances. There were some tech bulletins on the very early /6 temp sensors and gauges because they tended to show high temps.

Same thing about the thermostat.... I doubt the '69's was pulled out and put in the '65. If the '65 has a bad one or it is installed backwards, then it will overheat.

So there are 2 items that need to be checked before you go any further.

Also, either borrow an infrared heat gun to check the top of the radiator to see the real coolant temp or use a candy thermometer in the top of the radiator inserted in the rad cap's hole.

As Bill sez, I doubt the engine would not have been hot tanked. But as an FYI hot tanking does not get all the rusty crap out of the water jacket. An acid tank dip is needed for that.

If the t-stat or temp sensor don't fix this, then ask the builder if the head and block were checked for cracks. And ask what head gasket was used and if it was installed unmodified (as it should be).
 
... ask what head gasket was used and if it was installed unmodified (as it should be).
Recalls a story of one of my big screw-ups. When I was a brash youngster just out of engineering grad school but with dumF kid automotive knowledge, I had the head rebuilt on my 69 Dart 225. I looked over the block, head, and new head gasket and figured the head gasket wasn't correct for my engine because it blocked off a hole near the fwd end, so I drilled a hole there in the head gasket. Engine fired right up but after 5 min idling I saw the temp gage going off scale. I finally figured those were casting core cavities and the gasket was supposed to block them off. At least everything was still clean so I was able to lift the head w/ manifolds installed and swap in a new head gasket (w/ slight cleaning) and no more issues. That was 1985 when knowledge was tribal and often wrong. You youngsters can't appreciate how much the internet makes knowledge and parts available.
 
I purchased a new sensor for the 65 engine. I have on order a temp gun. The car has never spewed antifreeze and the rebuilder put in freeze plugs that blow out once the car gets too hot. I drove the car about 250 miles round trip the gauge flutulated between hot and very hot but no boil over. The gauge worked perfectly before swapping engines.
 
Do you have the PN for the new sensor? Some of the listings are incorrect. Do you have an ohmmeter? If so, you can take the wire off the sensor, warm the car up to hot, and measure the resistance through the sensor and list it; I can probably tell you if it is waaay off. And, I would now take the '69 sensor and put that in and see what the gauge shows; in that waym you are comparing both engines with the same sensor/gauge/limiter combo.

But using the temp gun or the thermometer is really what you need to do to see what the temp really is. We can mess around with sensors but the limiter and gauge are part of that equation, and you don't realy know precisely what the temp is with ths stock system.

The core plug blowing out hot is inconclusive, it just may not have been put in well. They rarely ever blow from hot coolant.
 
There is no such animal as a freeze plug that blows out when over heated. He probably put over heating discs on the freeze plugs. Pretty common practice. A freeze plug that would blow out when over heated would be the most mega retarded thing in the world. That would just empty the coolant and further contribute to a total meltddown. Stupidest thing I ever heard.
 
The 69 engine is long gone. I should have mentioned that the rebuild was 3 years ago but with health issues the car probably has less than 700 miles on it. Each summer I try to solve this issue but it is hard for me to work on the car. I have had 4 total knee replacements on the same knee and now need a 5th.
 
Ow! Sorry to hear about the knee! OK, I would urge you to start with finding out the actual temp when the car's gauge is indicating hot with a infrared gun or thermometer... there's nothing like having known good data when trying to solve a problem LOL.
 
There is no such animal as a freeze plug that blows out when over heated. He probably put over heating discs on the freeze plugs. Pretty common practice. A freeze plug that would blow out when over heated would be the most mega retarded thing in the world. That would just empty the coolant and further contribute to a total meltddown. Stupidest thing I ever heard.
Maybe they greased the plugs for easier installation....LOL
 
I looked over the block, head, and new head gasket and figured the head gasket wasn't correct for my engine because it blocked off a hole near the fwd end, so I drilled a hole there in the head gasket. Engine fired right up but after 5 min idling I saw the temp gage going off scale. I finally figured those were casting core cavities and the gasket was supposed to block them off. At least everything was still clean so I was able to lift the head w/ manifolds installed and swap in a new head gasket (w/ slight cleaning) and no more issues..

That's funny! I just put the head on my rebuilt 225 last week and took a good look at that same hole! Luckily I still had the original steel factory gasket handy and laid one gasket on top of the other. So on it went.

I'm not convinced the OP actually has an overheating issue.
 
I scanned the top of the radiator where the hose goes into the radiator and the temp gun showed 155 - 165 degrees the thermostat housing showed 162 - 175 the bottom rad hose showed 130-136 degrees any hints
 
I scanned the top of the radiator where the hose goes into the radiator and the temp gun showed 155 - 165 degrees the thermostat housing showed 162 - 175 the bottom rad hose showed 130-136 degrees any hints

It's not over-heating...???
 
Was the engine well heated up? If the gauge was reading high at that time, then the gauge or sensor is clearly off. The thermostat was just barely opening if the t'stat housing was that cool, so that is an indication that things are flowing well. The temps drop to the lower hose sounds OK.

Go get a TS6178 sensor from NAPA and put that in and see how the gauge reads. That will cause the lowest readings of any common sensor used in that application. But even with that sensor, my gauge reads at the top of the normal range when on the interstate in 80-85 degree ambient temps but the coolant is at about 198 degrees so it is OK.
 
The car was running for about 15-20 minutes. The needle was 1 line from the end of the gauge. It was pouring here in NJ and the Dart doesn't go out in the rain, lol. I will see what my numbers are once I get it out on the road. Thanks to all checking in. I will get the new sensor to see what that does.

Thank you all so much.
 
try running it once without the thermostat in it and report back


it may not be opening fully
 
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