Stryker412

My 84-- 305 motor, no computer, no cat, everything was removed prior to me buying the car recently. Just to give an idea of the car. It's like working on a 70's car under the hood!
My radiator kept losing fluid, the core looked horrible, was time for a new one.
Changed my radiator, brand new one!!... new thermostat, new rad cap.
No leaks anywhere, not losing fluid at all.
Good heat, running a 180 thermostat, aftermarket gauge shows about 190. I think it's off a bit.
Took it for a ride, all is good.

For except, the top hose is not building up pressure. I can squeeze the hose when at operating temperature.
When I shut the car off and it sits for a few moments, then the top hose has full pressure???? After the motor being turned off???
If I start it back up, let it run for 30 seconds, no pressure on the top hose again?
Heat works great. No leaks. Is this okay?? Rad stays full the whole time. Not loosing any coolant, stays full!
Seems odd to me!
Could it be air in the system?
Maybe the new rad cap I bought it bad? If thats possible...16lb cap, Stant
My oil is clean and full, anti freeze is nice and green, blows no smoke.

sofakingdom

iTrader: (1)

Sounds fine to me.

The cooling system ALWAYS heats up more when the motor is turned off; after all, the castings are just as hot as they were 2 seconds ago, but the water quit moving. Then once it starts up and cooling happens again, the temp (and therefore pressure) should indeed go down.

Sounds like yours is doing what it's supposed to.

-=Z28=-

iTrader: (3)

Whats the bottom hose feel like. You should have even pressure throughout the system. The only way that top hose could NOT have pressure in it is if you had a blockage.

The system has equilibrium. If the bottom hose is hard, the top one has to be. Vice versa.

Some hoses are A LOT softer than others, especially when hot.

Id throw that 16# cap away and get a 7#. 16# is a lot of pressure on your system. Hell, back in the day, they didnt even have pressure caps/system like they do today.

Stryker412

Wow, I feel like an idiot. I thought I was supposed to have pressure while it was running at full temp. Sorry about that!
The bottom hose feels the same, just a little bit cooler.

Checked my anti freeze today. Nice and clean, and not low. Good heat. Runs good.

I need to find the numbers on this 305 somewhere? The prior owner bought it that way. I have no idea what this 305 came out of.
I would like to know what year it is, and what its out of. Just so I know in case I ever need a water pump, fuel pump, or something. Even for setting timing....etc.

I had no idea on the 7 pound cap. I went to advance, and he said the computer stated a 16lb cap was stock. I had no idea. Was 7lb factory?



,

Ron U.S.M.C.

Is there a middle of the road cap with like 12 pounds or so ?

sofakingdom

iTrader: (1)

Use the 16 lb cap. It is stock. Nothing wrong with that. Leave it alone. A lower pressure cap is NOT a good idea.

Don't worry about "what 305 it is". Water pumps are all the same (as long as you get the one for the correct belt system, i.e. correct direction of rotation), fuel pumps all the same, etc.

-=Z28=-

iTrader: (3)

Yeah, these cars do run warm, so a higher # cap is what it calls for and you should run.

Personally, I like my systems to run lower, which is why I use a lesser cap. But, my car runs at 180-190 max. Almost too cold.

-=Z28=-

iTrader: (3)

If you want to look your engine up, here are some examples.





This is where you find your #s





Heads.....





Example............

Stryker412

Okay, I will leave the 16# on there. Holding coolant now, seems okay. My gauges are odd though. Someone put aftermarkets electrical gauges in, and they don't even have a name on them. must be really generic.

I figured most water pumps would be the same. But you state about the direction. That was a concern of mine. can you tell by looking at the back of water pump if it would need changed, what direction it would turn? Like the power steering pump too, can be someone different. Just doing my homework in advance. I plan on keeping this car for a long time,....I was hoping to find out the year of the motor....etc.

Thank you! My motor has headers, so it is kind of tight to see some things.
I thought I seen the ledge at the front of the block on the passenger side. I may have to pull the alternator off. I tried to look on that ledge behind it, but couldn't see any numbers at all. But then again, it is hard to see with the alternator
in place.




.

sofakingdom

iTrader: (1)

Can't tell by looking at the back of the pump. You could if you took the back cover off though.

Water pumps for systems where the back of the belt runs over the WP pulley, specifically the serpentine (snake-like) system, run in reverse (CCW). Systems like yours where the belt runs over the pulley in the normal way run forward.

PS pumps always run forward.

I wouldn't bother with that number. All it will tell you, AT BEST, is what engine THE BLOCK was part of originally. It won't tell you what heads are on it NOW, what pistons are in it NOW, what cam is in it NOW, what intake and carb are on it NOW, or anything else useful about its properties NOW. If you can actually look up that number, you might be able to figure out what displacement it is; that's about it. Meanwhile, you can get that info easier and with less uncertainty, if you get the casting number. It's conveniently located in one of the most readily accessible spots on the whole motor, right out in the open [/sarcasm]: on top of the bell housing flange, behind the driver's side head.



Here's a typical one. Feel free to look it up. Last 3 are 509.

You'll also find the last 3 of that # on the block in several places; on both sides, maybe on the front.

Stock block for your car ended in 201.

novaderrik

once the car gets up to temp and everything equalizes, there should be pressure in the system with the engine running.. sometimes caps act weird and won't hold pressure for whatever reason...

i just had this same thing happen on an 01 Blazer i put a motor in... it got up to temp and just stayed there and it wouldn't build pressure in the cooling system while it was running, but the upper rad hose would get hard about a minute after shutdown. then i took it for a 10 mile drive, and when i got back to my house the system was properly pressurized and it works perfectly now and is sucking coolant in from the overflow as it cools down like it's supposed to... i don't know what happened, but it's fixed..

Stryker412

I will try to see if I can view those numbers. I bet I won't be able too. LOL But I will see if I can. I was hoping to find out what year, maybe a car/truck, I was told it was a 305, but they bought it that way. So they don't know either.

Exactly, every car I have owned, always had pressure after running, especially at operating temp! Mine did what yours did though. I did buy a brand new cap, I bought a Stant from advance. I am wondering if I got a bad cap though? I mean I guess it is possible. The cars running nice, so no complaints.

One odd thing though. I took it out yesterday, and my aftermarket temp gauge never moved. I let the car run for about 10 minutes, I drove about 3 miles, and had heat. Should have moved. But the gauge never moved at all. Then all of a sudden, my temp gauge shot right up to 180, like superfast.

I am wondering if I still have air in my system!!! Like maybe the air pocket was where the sensor was, then the air pocket moved, and the water hit the sensor. I don't even know if I just made sense.

Stryker412

I don't know what changed. As it happened with novaderrik.

But....I let the car sit for about three days. I have been busy with other stuff. I just decided to take it for a ride.

I checked all the fluids...etc. Went for a ride, and now I have pressure to the top hose when warmed up, and the top and bottom hoses are equally hot. Fixed itself?

The bottom hose is slightly cooler though, I can grab it, the top one hot, but I can grab and hold it, but it is hot. It just fixed itself?? I dunno. I guess I am good.

My gauge is still acting goofy. It worked when I got the car a few weeks ago.

I have to find good gauges. Unless something odd is wrong.
My generic aftermarket gauge that is electrical, put in by the previous owner. Starts at 130, as a starting point. It worked fine before.

Now, it just stays at 130 way longer than it should, I even have heat in the car, 20 minutes of driving, completely warmed up, and faster than you can blink your eye, jumps straight to about 190! Not even like it is stuck, just as in, "Oh yeah, I am at 190 now"...within a split second. I guess my gauge went bad, I dunno.


.

sofakingdom

iTrader: (1)

Sounds like your aftermarket gauge is connected somewhere on the downstream side of the thermostat; in the top of the water outlet, for example. So the water at that point is cold until the stat opens... at which point the gauge sending unit (or bourdon tube, as the case may be) suddenly gets flooded with hot water. The behavior you describe EXACTLY matches that specific incorrect installation location.

Just one more reason that "I have an aftermarket gauge" DOES NOT automatically mean that you know what the cooling system is actually doing, any better than you would with the factory gauge in the head casting.

At this point it sounds like you have successfully outsmarted yourself over this matter. Since the car seems to work fine - runs at a normal temp, doesn't spew coolant, etc. - probably best to just leave it alone and drive it.

No you don't, and didn't, have "air in the system". Doesn't happen in this type of motor unless something REALLY STUPID is done when choosing some part, which is inevitably non-factory. If it's factory, or direct replacement in the factory configuration such as from a parts store, it won't happen.

Stryker412

'
Your right, that is the exact behavior it is doing. Just like. "POW", he comes the water!! And up goes the needle. Mine factory just had idiot lights I see.

I checked my water outlet, its not there. But I haven't searched for it yet. I will have to look around, and see where it is. I am curious to know. And if I should move it?

You are right. After it does its thing, it is honestly running at 190, although I have a 180 stat in it. But runs nice, and fluids are all good. Makes me happy!!