I replaced all the coolant hoses on my wires 2007 s40. The 2 coolant recovery tank hoses I used regular 3/8 heater hose now it acts like I have a blown head gasket. On the old hoses there is a fitting in the middle of the hose. Is that necessary? With out them will there be to much flow. They look like a restrictor.

 

I'm not sure what you mean "acts like I have a blown head gasket". If you happen to need to refill the coolant tank, it probably means you need to burb the system as your refill didn't get all the air out. If you are questioning the sizing of the small hoses to/from the coolant expansion tank, if the new hose fit on the nipples securely then its properly sized. I know on my 2000 S40 the hose from the upper radiator hose to the coolant tank is simply a straight of hose - not much can go wrong there.

 

I'm talking about the hoses from the tank to the back of the head and from tank to the radiator. The factory hoses have splice in the hoses at the middle of them. When I cut the hose at the splice the black connectors have a reducer in them. Is that to slow the flow out of the head and radiator.

 

the factory hoses splice the overflow tank into a closed loop system to allow the excess pressure to be released into the overflow tank. Its there to manage pressure so the small hoses don't carry an active flow. So in a sense you are correct the ports are to regulate (more like limit) the flow.

 

I really appreciate you letting me know that. Without the restriction in the hose would it flow to much pressure and coolant and make it seem like a blown head gasket? Thank you

 

still don't know what you are suggesting by "seem like a blown head gasket". I've seen cars overheat and blow off the top of the overflow tank, blow a hose off the overflow or even crack the overflow tank but all that does is cause a boil over. To me a blown headgasket would present as a loss of coolant with no other apparent leaks and perhaps accompanying white smoke and an odd sweet smell to the exhaust, or exhaust gasses in the coolant (a test kit is available to check for HCs in the coolant), or oil in the coolant, perhaps coolant in the oil (frothy dipstick and filler cap), misfires or high pressure in the coolant system. Not sure what you would have done to mess with the radiator hoses that would cause any of that. Did you try to manufacture a fitting versus just installing factory hoses? If you saw a drop in coolant level after changing hoses or draining some coolant out, but the car was normal prior, then you simple have air in your system that needs to burp out.

 

Not the radiator hoses its the recovery tank hoses. I'm talking the small hoses off of the tank. Will it flow to much without restrictors in them. That all I'm asking.

 

I looked at an upper radiator hose for my 2000 S40 and the nipple that connects to the expansion tank has a small port ~ 1/16 of an inch or so. The whole idea of the expansion tank is that as the coolant heats, it expands and the expansion tank gives the closed system the space for the coolant to go. When the coolant cools, the vacuum pulls it back into the main cooling system. Newer cars like your Volvo use this design so as to not have air in the radiator or coolant flow paths. The expansion tank gets pressurized the same as the overall system (which allows the system to raise the boiling point of the coolant) but its not designed to have coolant circulating to the tank. Will not having a restriction cause issues? I have no idea but it seems plausible that allowing a flow of coolant through the expansion tank could allow some air back into the flow paths which can create air pockets. Considering the whole idea of the design is to allow small amounts (ie a pint or less) to bleed out of the main flow paths, why would you do something to open up the path?

 

Let me boil this down to its simplest version...

Fact 1: You changed something
Fact 2: The change created a new problem
Solution: Change it back

It's really hard to out-engineer the folks who designed our Volvos originally, so I can't see a reasonable alternative to just putting the car back to its original state.