Well I finally figured out that my bottom radiator hose is coplasing at 3,500 RPM's or higher and causing the engine to become warmer than I like to see around 230-240. I took the car to a good mechanic that only uses genuin GM parts but they claim there are no "springs" listed for my car engine 88' 350 TPI. The dealer won't touch it beacuse it is "modified" 88' TPI in an 89' RS. Anyone know where to get a "spring" to reenforce the raidator hose?? Or maybe a p/n or what it is "technically" called?? P.S. I have the blue goodyear hoses.

You've actually seen it collapse? If so, you can purchase a universal radiator hose from most parts stores with a spring inside. Just measure the diameter and length you need and you can probably find one.

ya. just goto autozone or another parts store and pick up a hose for a 88 350.. it should have the spring and fit perfectly

I would steer clear of autozone atleast. I just picked up a lower radiator hose from them and it is a soft piece of crap and no spring. I am going to get a universal like was mentioned to get the spring and becuase it will hopefully fit my Griffin radiator better. Unless they have a different hose for an '88 350 vs. an '82 305. Maybe other autoparts stores hoses have the spring. Just look in it before you put down money.

Yeah, just buy a new hose.

Well ok I just bought the goodyear hose set. But live and learn I guess. I'm heading out to get what I really need.

you could get a coat hanger and wrap it around a piece of pvc pipe that is the same OD as the ID of your radiator hose. then coat it with something before you put it in so it won't rust away. might save ya some headaches, time and a few bucks on a new hose with the spring in it already.

when mine was collapsing and i couldnt find a spring i took a peice of brass or copper(?) tubing that was almost the same diameter as the hose and its about 4-5 inches long with a small curve. it fit perfect in the middle, where the hose itself curves(with a little work) and hasnt collapsed since. But a spring is easier i guess

Good idea I didn't think of that.

You must have air in the system for the hose to colapse. Without the air the hose could never collapse because water is incompressible. And the water from the collapsed hose has to be going somewhere else.

With air in the system the water pump at high speed will pull a low pressure in the suction, and pump the water into the top hose of the radiator. which at low speeds would hold the air, if any is in the system.

Have you checked the radiator cap little one way valve is openning OK, it isn't supposed to need hardly any vacum in the cooling system to open and let in water from the haeder tank. The cap has two valves, the other one is the higher pressure one to build pressure in the system.

If the little valve sticks, you will not get a fully primed cooling system. The top radiator hose can only become full of water after the engine has heated and cooled several times, because it is above the radiator cap.

Not to burn you, but the hose can still collapse with just water in it. Even if the entire cooling system has no air in it. Try this. Take a straw, suck some water into, put your finger over the end of it and try to suck the water out. What happens? The straw collapses. At high rpm, the pump is trying to flow the water at a certain rate, if it can't, then a pressure difference arises across the pump, with the lower pressure being on the lower radiator hose. If that pressure gets below atmoshperic pressure, the hose will collapse unles it has a spring in it.

Anyway, I just had to replace my lower hose for the same reason. I got a hose from Advanced Auto Parts and it has the spring in it. It replaced a hose I got from Autozone a year ago with no spring in it (I forgot to check).

-Dave

Well I double checked it and the hose doesn't completly colapse but the hose shrinks to about 1/2-1/4 it's normal size.

Hi A sucked straw is agreat example of why there is definately air in the system. When we suck on a blocked off straw it collapses because water is being taken out of the straw, just like the pump is doing to the bottom hose. But when we suck on a straw with its end in water it doesn't collapse. it only copllapses if we we don't put any water back into the other end of the straw.

The cooling pump sucks on the system but as fast as it sucks it also pushes the water around the engine. If there is no air in the system as much water that comes out of the hose, has to go back in, unless it has some where else to go. Water will go straight back into the bottom hose as quickly as it came out. Where else would it go.

But. When there is air in the system instead of the water having to go straight back to the bottom hose, it can hang around a while where the air used to be because it can easily compress the air.

So it is not the low pressure in the suction that causes the problem, but the high pressure in the discharge compressing the air. The symptoms though are a collapsed bottom hose, and the impression that a stronger hose is needed.

Also the faster the water is sent around the system, the more resistance the water meets. So at high speed, the system resists the water flow more creating the back pressure on the pump and the higher pressures in the engine and top hose.

Check the radiator cap for a stuck inlet non return valve. If it is stuck the engine will not suck in water to replace the air. Honest.

hm. this is an interesting thread.. What Andy Bush is saying does make sense... maybe the radiator cap isn't keeping the pressure in and might be causing it...

EDIT: i just reread Andy's post and i see he already covered the radiator cap thing.

Hi

Hi Again
The cooling system needs to be under about 14 pounds per square inch (psi) pressure when it reaches 200 plus degrees F.
If you can squeeze and flatten the top hose when the engine is hot or cold - MIND THE FAN - there is air in the cooling system somewhere.

Major problems occur with air.
You get corrosion in the cooling passages.
You get hot spots in the cylinder heads which can crack them.
It can stop the coolant system reaching proper pressure.

The pressure in the system is very important. If the engine does not get to about 14 psi the coolant will boil, but only where it touches hot metal, just like in the bottom of a sauce pan. When that happens the metal gets too hot, and you again crack heads send cylinders oval and generally run up expensive repair bills.
You cannot tell this is happening, because just like in the saucepan, the steam bubbles re-condenses into the coolant.

The pressure stops the coolant boiling. It does this because the vapor pressure from water - what makes it eveporate - increases with temperature. When water gets to about 212 F the vapor pressure is 14.7 psi which is the same as atmospheric pressure, and the water boils. So if your pressure cap is not working, you can boil off al the coolant on a long journey - which is why so many cars used for years around town, overheat on long vacation trips.

If you drive up a mountain the atmospheric pressure reduces, and if you have a tired radiator cap, it will let the coolant pressure drop and the engine will boil over even before it gets to normal operating temperature. Add the extra effort of going uphill and the radiator cap becomes the single most important part of the car when going skiing.

The Camaro system is designed to be self purging of air. It has to be because the top hose is higher than the radiator filler. When the engine heats up, the air expands and creats enough pressure to pass through the expansion valve in the radiator cap into the header tank and then to atmosphere. The cap on the header tank is not a pressure cap - at least not on the older models.
When the engine cools, it sucks coolant from the header tank. It keeps doing this until all the air is out and replaced by coolant. This means when you refill a cooling system a lot of coolant needs to keep being added to the header tank for the first week.

Garages do have a machine to purge the air.

Once all the air is out, all the valve does is let small amounts of water in and out but only because of the exapnsion of water with heat, not because of steam or air. This is when the small inlet valve can stick. That again is not noticed though until the radiator needs refilling after maintenace like changing the bottom hose.

After thinking about it for a while, I agree wit hyou Andy on there being air in the system. I forgot one little thing in my previous reply, and that is that cooling system is a closed loop. If the system wasn't closed loop, then the radiator could collapse without air being present, but sine the pumps discharge goes right back into its intake, it shouldn't collapse unless air is present.

I still say it could collapse, regardless or air, if the radiator was blocked, or there was a big restriction in flow at higher rpms. But then the person would have serious overheating problems. Replace the radiator cap, I thought mine was fine, but after I replaced I can't squeeze the upper radiator hose after my car warms up. So I know the system is pressurized now.

I'm really surprized those goodyear hoses didn't come with a spring. Especially considering how much they cost. I may rethink buying them in the future.

-Dave

That is a very interesting point.
That's true, if the radiator was blocked, the pressure would build up under the radiator cap, and force the water out of the cap instead of sending it back to the engine. Then I agree you would get a collapsed bottom hose.
What a fascinating thread. This is a great forum.

The example of the suction on the straw is exactly right on.
I'v seen many marine systems on yachts where some barnacle
brain has used a replacement hose on the SUCTION side a pump
system and the hose gets sucked flat! why? no spring to keep
the hose from collapsing. A hose does not need air inside to collapse. it can collapse while filled with liquid and if it is on the suction side of a pump. some marine exhaust and water intake
hoses have the spring built in to the rubber wall of the hose...
you never see the spring until you try to cut the hose with a
razor knife. surprise!!

Hi The marine engine suction is below atmospheric pressure, otherwise no water would go into the pipe. All suction hoses like that are stiffened against collapse.

But in a closed circuit car cooling system, the radiator cap lets the whole system get to about 14 psi guage or 28 psi absolute.

This means that even the suction hose will be well above atmospheric presure if the system has no air and the radiator cap is working.

If the hose collapses the pressure inside must be below 14.7 psi absolute, which is half what it should be, which definatley is not good for the engine.

The lower hose may be stiffened to stop it whirling around and fatiguing, also when the engine cools, it will help the radiator cap open and let in replacement coolant. But if it collapses when the engine is running, it shows a problem which is due to the cooling system being well below the proper pressure. That happens with air and with faulty radiator caps, or a leaking system.

I am thinking, offhand, that you are over-idealizing the system. In the described closed system, all that is required for the suction hose to shrink is for another (or others) to commensurately swell--the system as a whole is still balanced as the volume of the fluid remains (relatively) constant. I agree with your comments about the likely faults, however; but add to them a badly swelling hose somewhere else in the system.

I guess if the top hose swelled up a lot, the lower hose on a cold engine would collapse, but that is't what people are reporting.

The important thing about anyone seen the bottom hose collapsing when the engine is hot is it means the system is not getting up to pressure. That is most probably due to either air in the system or a leak.

Overheating and the lower hose collapsing means the hose collapse is a symptom of no pressure, and not the cause of the overheating.

The radiator cap has to let the system vent and reprime with coolant, so it has two valves built in. They seem to stick sometimes and that sounds like a common problem.

Yikes... Just spent a couple hours reading a few hundred references on the web.

High rpm engine operation can yield coolant flow pressures in excess of 30 psi on the 'high' side of an automotive water pump in even a sealed system. This would have the possibility of overcoming even a properly operating pressure cap of 14 psi gauge (at sea level -- worse at higher elevations). If the hose is unreinforced or at its design limit it could then collapse. The collapse strength of the hoses deteriorates over time as well.

Here is a good general web reference on automotive cooling systems. It appears to be a 37 page chapter from a Navy automotive training text.

http://www.advancement.cnet.navy.mil.../14264_ch6.pdf

This is a fascinating thread.
There is no doubt that the lower hose can collapse under various conditions. People are watching hoses collapse .

In the thread a number of the causes of the collapse were discussed.

The system may have air in it.
The radiator could be restricted and backpressure the pump enough to open the radiator cap and let water out.
The system could be cold and not up to pressure.
The system could have a leak.
The system may be cooling down and trying to draw coolant back from the header tank.

The value of knowing this, is the connection between seeing the lower hose collapse while the engine is running fast, and the engine overheating. The collapse will of course not help the cooling, but something else is causing the collapse and the overheating.

My bet is 80% of the problems could be fixed with a new radiator cap.

A centrifugal pump like the engine coolant pump will only develop a pressure when the flow on the outlet is backed up to create the pressure. If a cooling system was not designed to let the water circulate easily enough to avoid building up a higher pressure than the radiator cap could hold, the cooling system would be ineffective.

“The important thing about anyone seen the bottom hose collapsing when the engine is hot is it means the system is not getting up to pressure. That is most probably due to either air in the system or a leak.”

“Overheating and the lower hose collapsing means the hose collapse is a symptom of no pressure, and not the cause of the overheating.”


Not necessarily. Or sorta.

A cooling system could be up to pressure when it is hot and still have the lower radiator hose collapse. If there were a leak *into* the system of combustion gases (‘leak’ heretofore seems to have implied *out-of* the system) the added pressure could overwhelm even a brand-new, in-spec pressure cap. But the presence of the compressible gases could allow the system to locally or regionally vary in pressure sufficiently so as to allow the suction of the properly operating centrifugal water pump, in an otherwise normal and in-spec system design, to collapse the lower radiator hose. But you do allow for a 20% probability of such untoward scenarios.

And, no, this particular group of symptoms is not precisely what David reported in this thread but a search reveals that he has mentioned them in others spanning the time period since his TPI engine swap.

“If a cooling system was not designed to let the water circulate easily enough to avoid building up a higher pressure than the radiator cap could hold, the cooling system would be ineffective.”

Well, yes; this is a bit tautological. It could also be that GM wanted to save a few pennies on each car and eliminate some valuable but perhaps initially redundant overlap in the design (wire reinforcing in the hose). Or redundancy that is only initially needed on a very small percentage of new vehicles whose system’s collective tolerances negatively push outside the design spec.


David, besides the excellent suggestions that Andy has offered, some things are still not 100% clear from the collection of independent posts/threads you have regarding your ongoing overheating problem*:

*[And possibly related intermittent flattening of power above 3500 rpm… Aside: have you tried running sans the MSD system, i.e. using the stock ignition system? This sort of flattening is sometimes indicative of an aftermarket ignition system failing. You don’t specifically mention it, but I am inferring that you swapped in a good TPI fuel pump in place of the TBI – right?]

Have you, or the repair shops you have visited since, back-flushed the radiator (you mentioned at one point that you had not done that)? I am musing that it sounds like your transplanted engine sat for an extended period of time. It could be that, despite your desert environment, this allowed internal corrosion to set in (or further progress). When you installed and operated the motor this corrosion could have been swept up and then clogged an otherwise good radiator. This in itself could factor in the extra internal flow resistance needed to collapse the hose.

Do you know the history of the transplanted motor? You speculated yourself that there might be a crack in the block or heads or a blown head gasket. Sometimes the reason a car with a still running engine ends up in a wrecking yard (or for sale!) is that the cost to properly repair a fundamental problem like overheating greatly exceeds its value. Following this train of thought, did you or the various shops test for the presence of combustion gases in the coolant and rule this out? It sounded like the bubbling problem might have ended when the proper rotation water pump was installed (?) but I am still wondering.

Lastly (but certainly not exhaustively with respect to troubleshooting your problem), is it possible that you added multiple doses of radiator sealants before or after the swap? Excessive amounts could clog an otherwise good radiator and if they are still present in the fluid they could change its viscosity just enough to wander outside the centrifugal pump design specs. It might also be that the previous owner of the car did this and the sealant components lay in wait inside the block (I don’t know how or whether the various formulations are resoluble to any extent, etc.).

HTH