RENIX- Major failure - now new h2o pump, thermo - now hot?

Had the most major problem of my 88's career. Water pump failed, throwing the pulley forward a half-inch, tossing the belt. My experience was: temp gauge pegged into red out of nowhere, steam into cabin and from under hood, power steering loss, clunking.

I got it to the shoulder of the interstate, realized the problem, pulled the belt off and let it cool down. The pressure bottle was like a balloon and it was blowing steam out of some fittings (like up the heater core area mostly).

I could only go a half mile at a run before it got too hot. Then I'd let it cool enough to try again. Eventually got it to a park and ride. My Dad was able to bring me a new pump and 195* thermostat + fluids, etc. I had the tools.

Finished up at about dark and drove it the last 2 hours home. It ran hot, but not overheating.

Before the failure, the system ran at almost a full notch under 210, staying there almost no matter what.

Now it got to that point, opened the thermo, then very gradually climbed up to 210. I threw on the heat the rest of the trip home and it sat right at or slightly above 210.

I think there is air in the system yet. No leaks have shown up and it was consistent in its temp, just a little high.

I did burp the system with the coolant temp sensor pulled from rear of block/ nose downhill/ fill bottle until coolant comes out/ replace sensor. I'm not sure I let enough coolant/air run out though.

Does that sound like the right line of thought? What else could cause this higher operating temp? The new thermo shouldn't affect it, right (it just opens at the right temp and the system does what it does after that-right?)?

Oh yeah, so the history now is: new hoses, bottle, freeze plugs about 2 years ago. New fan clutch a month ago. Temps stayed just over the notch before 210. Now, new water pump, new 195 thermo and temps to 210 and over.

I think it's air...

I burped it really well tonight and just got back from a test run. It got up to where it used to run, opened the thermostat and dropped, then climbed up and settled where it used to run. Then it slowly began creeping up again all the way to 210 and beyond on the interstate. At lower speeds it runs at 210 fine. On the interstate it gets well above 210.

I think something that blew in the initial meltdown isn't holding pressure. I'll keep my eyes open for leaks, but nothing came last night.

What is going on!?

It's just a new water pump and 195 thermostat (which seems to be working as it should). I put the hole in the thermo in the up position. Do I need a special one for the RENIX?

If something isn't holding pressure, shouldn't it also leak after I park it hot? No fan or airflow change whatsoever.

It seemed to do fine for about 5 miles at 65mph, then slowly climbed up to way over 210. Does this sound like pressure loss to anyone?

Anyone?

Search my old threads on "radiator Renix overheating" for good ideas.

I discovered that the Renix OEM set up tends to trap air permanently in the top half of the radiator. I solved the problem with an inline filler neck added to the top hose.

All the other uusal suspects need to be checked too, but the Renix plumbing layout was big mistake, no way to bleed air out of the top of the radiator. You can burp it tell the cows come home and still have half the radiator, top half, full of air.

Will running it with the pressure bottle cap off bleed air ok? I had this thing working great for 2 years, then the water pump exploded. Now I'm fighting with it again.

Just noticed it's leaking at the water pump gasket. I didn't have the torque specs in the park and ride where I did the work. I just went with what felt right without overdoing it. The bolts backed out a little too and now it's leaking.

I'll go through all the bolts again tomorrow and make sure they are 17 ft/lbs.

Will running the motor with the cap off do me any good? I've already burped through the temp sender twice with no luck.

The coolant rez cap is surely toast at this point. Replace it with the Volvo cap. 703-1396 at Napa. After, of course, you've fixed the water pump leak.

I already have the green Volvo cap and it held pressure beyond the fittings, etc that steamed. The bottle is a new one, very rigid, but it blew up like a balloon. No leaks detected there, but it could have very small cracks that seep under pressure.


Anyone think it'll work to run the engine with the cap off in order to get air out?

HenryKrinkle said:

Anyone think it'll work to run the engine with the cap off in order to get air out?

Click to expand...

NO.

Be sure to remount the water pump, use a new gasket, and CLEAN the old gasket surface, and the old bolt holes before you re-mount it all. You can try filling it all by removing the large hose at the top of the radiator, and using a short 90 degree piece of old radiator hose loosely fit on the top radiator fitting as a fill funnel, but it is messy and wasteful of coolant when you remove and swap the hose connection and it still traps a lot of air in the top radiator hose. Air does not like to go down hill against water due to density differences. The air wants to rise and stay trapped in the top of the radiator and top hose.

Just discovered my radiator developed leaks in more than 1 place. I'll get to searching about radiators, but can you guys recommend a good one? I don't really want one of those cheapy alum/plastic ones.

How did you guys modify the closed system to allow better burping?

Get the all brass and copper 3 row radiator, CFS brand.

Details on the inline filler neck:

http://www.naxja.org/forum/showthread.php?t=1000460&highlight=Renix+radiator+filler+neck&page=3

And a good read on Renix overheating, and trouble shooting and other fixes:

http://www.naxja.org/forum/showthread.php?t=998371&highlight=Renix+radiator+filler+neck

Ditto on the copper radiator. They are also rebuildable where the aluminum ones aren't.

Put a later model thermostat housing on that has a tapped hole. Put a radiator petcock in the tapped hole to bleed your cooling system.

cruiser54 said:

Put a later model thermostat housing on that has a tapped hole. Put a radiator petcock in the tapped hole to bleed your cooling system.

Click to expand...

While that may help at times, it seems to be little help if the thermostat is closed and with the screwy way the upper radiator hose is made (sort of doubled over), it acts like a plumbing P trap on drains, and blocks the air flow in BOTH directions. That is why I finally gave up and went to the inline filler neck about 4 inches from the upper radiator inlet. Also the turtle bottle and heater hoses already do a great job of bleeding the engine block (they bypass the T-stat), the real problem is that P trap like hose on the inlet of a cross flow radiator that has no air bleed on the exit side (or inlet side) of the radiator.

Once I put that inline filler neck on mine, my operating temperatures dropped about 30 F peak on a fresh refill!!!!

I guess you could try fiddling with the upper hose for an afternoon, moving it up, down, and around to try and get air to go up stream and out and into the vent hole, but I tried it with the hose disconnected from the T-housing (lifted the hose straight up) and it was still a messy pain that left 3-4" of air trapped in the upper areas on the radiator side as it is higher than the T-stat housing, and during the reconnection air get backs in.