04 Buick Rendezvous over heated last night. I pipe-wrenched the rad-cap off to find no hole. just inches of brown mud. I assume it is engine rust. this car has never been flushed in 220,000 miles. do

old old old car.38 years later.

when did it last run good, last week , last yea,r last decade/?
fast idle is vacuum leak, or bad IAC. 1500rpm cold is normal not 3000
overheating has many causes. (huge) need a list or just wan to buy tools to test it and find it.> ???
gue$$ing is hard, work and a real slog. hear goes 1 slog1.
due to age here is the list (a test each)

running 38 year old antifreeze? Lol ?
38 year old thermostat? 7 years is design life EOL ,oops.

engine compression test passes? 180-PSI? wot done?
rad and engine block flushed out of red rust mud.
38 year old water pump is no good nor is the belt. now.

RaD LEAK DOWN TEST, A TOOL; PASS OR FAIL.?
RAD , gas test (exh) a tool that see exhaust fumes in the RAD coolant, green/blue tester all shops have all this here. I typed.

water leaks anywhere under car or passenger toes. , not the side tank blow out you told and is clear
see milk-chocolate for oil in pan, oops leaks. coolant.
see milk-chocolate in tranny pan (did sticked , oops)
Rad CAP must be replaced this old. the rubber gasket in it is dead.
next is see oil or carbon dust in the RAD neck cap off dead cold engine. and full to the top of said neck. (free test eyeballs)

ok all is good above and does it overheat only parked or driven or both or only AC on. or all the above, I bet yes all.
if overheats parked, the fans must all be good are they.?

If still overheats we use IR gun tool and run the beam ever every inch of RAD TUBES. and must show 50f degree variance or more
per tube end to end if not that TUBE is clogged up, RAD BAD./
that is all for now I can do more. if need be..

on simple cause is not checking RAD water level dead cold engine
and making sure that side spill tanks has good tubes inside and work (as engine cools it sucks back coolant.) if tubes bad fix them
or check coolant like 1929 days,RAD cap off. look cold.
Coolant expands naturally hot. that side tank captures it for next cool down cycle and bad rad caps to wreck this cycle.
full stop fingers tired.

pretend caddy here,,, funny then and Diane Keaton hot .(x100)

the bug only needs a fan belt to stay cool.... (owned 2, 1970 to now)

https://youtu.be/Xo2kSu6O8cU?t=2

keep cool.
the side tank blow outs are also warped heads and or bad headgasets
if you see STEAM at tail pipe end hot engine the head gaskets are bad. 1 or both. or far worse crack block.or cracked heads.
id have looked at the tail first. (steam in front yes, look in rear)

Did you get all the air out,remove radiator cap,start up.let run until the thermostat opens,you will see the flow in radiator,put cap back on and fill overflow container to full.

Possible trapped in system. Bleed system, should have two small screw bleeders, one in front of left valve cover on pipe behind water pump and the other on coolant pipe outlet as you follow upper rad. hose towards engine. Engine cool, remove rad cap, open both bleed screws and fill rad until coolant flows free out both bleed ports. close both bleed screws, rad cap off, start engine and let idle until upper hose is hot to touch , shut off, let it cool down for 20 minutes, top up rad and install cap. restart car ,drive and check.

water in the oil will turn the oil brown like mud,is that what you see? if so,then you have a blown head gasket,do not run motor if this is the case as the motor wiil spin a crank bearing or lock up.are you sure about the water in the oil? look for real brown oil just like mud with bubbles on the oil dipstick. if the heats stopped working it may be because the radiator's low on fluid. look in the radiator for low coolant,if you can't see the coolant when you remove the radiator cap,it's low. with engine cool,remove the radiator cap 1st then start the engine. do you see steam and fluid blowing up frome the radiator? if so,you have a blown head gasket in the motor. head gaskets can blow and leak water into the oil or oil into the radiator. or blow and leak into the exhaust sysytem and blow coolant out of the tail pipe. three different ways for a head gasket to blow. usually the head gasket only blows when the engine has been run really hot!!! hope this helps.thank you for choosing fixya .com

did you use your old fuel rail and injectors? salvage yard motors tend to get dirt, spider ****, and mud dobber nests in any open line while sitting. check all the electrical plugs on the motor to make sure the injectors are getting power. how long did the vehicle sit not running? could be the pump has rusted and frozen up from sitting.

Sensor A is going to be one on the exhaust pipe close to the engine. Sensor B is behind (or in) the catalytic converter. Now we need to know if it is on bank 1 or bank 2... you can get them off with s 13/16 socket or wrench.

http://www.fixya.com/cars/r6571076-blower_motor_not_work

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

I just did this job last week on my 2002. I was able to get the front two screws and one rear screw off the cowling over the crossover exhaust pipe and gave up on that approach when I tried to loosen the crossover bolts that were beyond difficult. I managed to loosen the black pipe above the crossover that carries the coolant and just pushed it up without removing that one either. To get the top bolt off the thermostat housing is straightforward and easy with a socket and short driver extension. The lower bolt toward the rear was possible by reaching from the rear with a standard half inch open end wrench and turning 1/12 turn and flipping the wrench over and back again to get it out. The first loosening was only accomplished by bridging a large screw driver under the wrench and levering it to get enough force. It takes a lot of effort to get it out and is backbreaking but easier than what they ask for in the manuals. The thermostat comes out fairly reasonably by having the slightly loosened cowling. I tried many times to put the back bolt in partially to reinstall it since there is a slot on that side of the pipe but to no avail. I was successful at putting in the top bolt first and then balancing the rear bolt in the box end of the 1/2 inch wrench and gingerly twisting it into position till I felt it go partially into the hole. With the tension from the pipe holding it in place I was able then to use the open end of the wrench to again tighten it 1/12 turn at a time. It took about three hours overall and that is what they claim it takes to do it their way but I felt this was more feasible for the layman given the inaccessability of the bolts and knowing what it is like to work with exhaust bolts without a torch. Best wishes for anyone who attempts this project. I read that a shop will charge around $450 and up for thermostat replacement. This is what used to be a 15 minute job on a normal car and still the parts are just $12 or so.7/5/09

I just did this job last week on my 2002. I was able to get the front two screws and one rear screw off the cowling over the crossover exhaust pipe and gave up on that approach when I tried to loosen the crossover bolts that were beyond difficult. I managed to loosen the black pipe above the crossover that carries the coolant and just pushed it up without removing that one either. To get the top bolt off the thermostat housing is straightforward and easy with a socket and short driver extension. The lower bolt toward the rear was possible by reaching from the rear with a standard half inch open end wrench and turning 1/12 turn and flipping the wrench over and back again to get it out. The first loosening was only accomplished by bridging a large screw driver under the wrench and levering it to get enough force. It takes a lot of effort to get it out and is backbreaking but easier than what they ask for in the manuals. The thermostat comes out fairly reasonably by having the slightly loosened cowling. I tried many times to put the back bolt in partially to reinstall it since there is a slot on that side of the pipe but to no avail. I was successful at putting in the top bolt first and then balancing the rear bolt in the box end of the 1/2 inch wrench and gingerly twisting it into position till I felt it go partially into the hole. With the tension from the pipe holding it in place I was able then to use the open end of the wrench to again tighten it 1/12 turn at a time. It took about three hours overall and that is what they claim it takes to do it their way but I felt this was more feasible for the layman given the inaccessability of the bolts and knowing what it is like to work with exhaust bolts without a torch. Best wishes for anyone who attempts this project. I read that a shop will charge around $450 and up for thermostat replacement. This is what used to be a 15 minute job on a normal car and still the parts are just $12 or so.7/5/09