05-20-2013, 09:58 PM #1
2004 MSX 150 anifreeze problem...
2004 MSX 150 anifreeze problem. I rebuilt the engine and took it out for a test drive and the cap on the oil heat exchanger off the water pump popped off when I accelerated. all the antifreeze came out and overheated the engine. I put the cap back on and cranked the hose clamp down good. went out for another test run and the same thing happened. why would there be so much back pressure to pop off the hose off the oil cooler?
05-21-2013, 12:39 PM #2
Hmm... that's unusual. There shouldn't be that much pressure. The coolant system operating pressure is 1 bar (14psi)... with a max pressure of 18psi.
Have you done a compression test yet? How about a leak down test? I would be concerned about the headgasket. On one I fixed, I did a leak-down test and was able to hear it gurgling the coolant... which made it clear the head gasket was blown.
After my rebuild I had a leak on the oil cooler coolant end cap (right side) and was loosing coolant. I pressure tested the system and discovered it. Needed to tighten down the end cap clamps again after running it up to temps. Fixed my problem.
An easy way to pressure test... pull the small hose from the coolant rail to the coolant jug. Plug either jug connector or the hose and put pressure to the other one (put jug cap on tight). I plugged the jug connector and Teed in my bike tire pump and a gauge to the small hose. Then pumped it up and watched the pressures. Don't put more than 18-20psi in it. When you pump it up you'll hear the coolant gurgling around in there... that normal. It should hold the pressure if all is well.
05-22-2013, 09:12 AM #3
new head gasket. just rebuilt the engine. pressure tested good. took out the thermostat and going to test it today
05-22-2013, 01:17 PM #4
What "pressure tested good."... the coolant system or the compression?
Have you done a leak-down test? Compression tests can't positively ID headgasket failures, but a leak-down test will. Made my coolant gurgle (blown headgasket).
I don't think a stuck t-stat would cause that kind of pressure build-up. There are other paths for the coolant to flow. Now it could have lead to overheating and boiling of the coolant thus creating lots of pressure... but I think you would have tripped the overheat warning/limp mode before it could get hot enough to do that.
05-22-2013, 06:16 PM #5
the water is leaking out around the intake side. it being forced out under pressure cus the whole area is wet. when I open the coolant tank there is a lot of pressure and the water is gone. the engine does give me the overheat symbol. going to look for a leaking hose or bad connection...but why so much pressure? I think I have to pressure test every component in that area.
05-23-2013, 09:41 AM #6
- Join Date
- Apr 2010
- Stamford CT
If you have not already done so, replace the crappy factory clamps (both ends) on the oil cooler. Their ribbed design lets the screw slip. Switch to a slotted design where the screw's threads firmly engage the band and protrude. I'd also double check all hose routing. Maybe something is crossed up. Lastly, if all of the above is checking out good, then the new head gasket is probably leaking. When my ski had low compression, it also blew off the same hose as you. I tried the easy new head gasket plan, but it did not work out for me. A new head gasket alone is rarely the solution for these Weber engines to low compression. The block (open deck) and head warp easily when over heated.
Like ripcuda suggested, start with a cylinder leak down test, it is the best source for the type of over pressure you are describing.
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