• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

No Pressure in Radiator Hoses

R

ReverendOD

NAXJA Forum User
Location
Fenton, MO
2001 XJ Sport
125,000 Miles

When I am up to full operating temp 195-200 there is no pressure in the upper or lower radiator hoses. Is this normal for these or is there something else going on here? Im going to pick up a radiator cap tomorrow and keep and eye on the overflow to see if its loosing coolant. I did check the oil both under the cap and drained a bit and there doesn't seem to be any water in the oil, nor does it seem to excessively smoke white.
 
Last edited:
Stuck thermostat will keep pressure from the upper hose and lower hose.

Bad water pump impeller would cause low pressure top and bottom.

Clogged radiator would cause high pressure top, low pressure bottom.

Try the cap first, but remember it is vented to release expanded coolant to the recovery tank, and vented to allow return of the coolant as the vacuum in the system is created by the cooling coolant (cooling coolant?).
 
I did notice when its warmed up and running if i squeese the upper hose i can hear and see it making noise in the resivour. Seems the cap may be bad and releasing pressure all the time. I did notice the small disc in the center of the cap feels real loose all the time. We'll see with the new cap what happens tonight.
 
Amen, ReverendOD :rolleyes:
 
Most people don't realize that the recommended replacement interval on a radiator cap is two years.
 
old_man said:
Most people don't realize that the recommended replacement interval on a radiator cap is two years.
Click to expand...

Huh really... yeah i just purcahsed this xj a month ago. Im also going to go ahead and have an oil analysis done when i do the oil change this week, see what they have to say about the oil and if there any traces of coolant.

Been considering doing a waterpump and t-stat replace also, according to the original owner neither have been changed.
 
ReverendOD said:
Been considering doing a waterpump and t-stat replace also, according to the original owner neither have been changed.
Click to expand...

Cap definitely, stat definitely (go 195 OEM style only) and pump is not a bad idea. Flush/fill entire system including the heater core while you're at it. Refill with conventional (green) antifreeze. 50-50 mix will give you protection down to -34 F and good overheat protection as well. Use a hydrometer to be sure of concentration.

I was just working on a 95 Camry a couple of weeks ago (no, not for unintended acceleration!) with the original factory radiator cap on it. Needless to say when hooked up to the cooling system pressure test just for grins (had a new one to replace), it didn't hold any pressure.

A radiator cap will set you back about $5. Change it at least periodically or immediately if it's a "new-to-you" vehicle.
 
Thermostat: Stant SuperStat Premium 195 degree.

Water pump: new, NOT reman.
 
Im also going to assume that the Negative Pressure Valve (the small brass piece in the center of the spring) should not be hanging loose either lol...
 
well the cap didnt bring back pressure to the hose but it did reveal a coolant leak from the waterpump possibly the weep hole. Picked up a new pump, tstat, gasket, hoses and coolant. Looks like i have a weekend project now.
 
You must log in or register to reply here.

Similar threads

G
Coolant System No Pressure
Replies
9
Views
2K
Woodswanderer
W
O
0331 Strikes Again...?
Replies
11
Views
296
Ol Blue
O
Root Moose
Cooling System Reset (2000 XJ)
Replies
1
Views
1K
Rob Mayercik
R
B
Reasons for white exhaust smoke besides head gasket?
Replies
1
Views
818
RCP Phx
R
X
Replacing my entire cooling system
2
Replies
23
Views
4K
RCP Phx
R
Back
Top