Bikespace

I'm requesting additional theories and things to check. Sorry for the text wall.

My wife's 79 suffered a sudden loss of power steering immediately after braking for a highway off-ramp (right turn). I've read a few other threads (all with stock Power Steering), and have a few ideas, but want to see what the Forum thinks. This is a 79 L48 Auto (despite the photos), with a Borgeson steering box, which was installed with all new hoses, and a newly rebuilt power steering pump. I don't believe the failure was related to the Borgeson box itself. Although this occured during a right hand turn, it is obviously not related to the stock steering valve, as the car does not have one.

After braking some more and muscling the car around the turn, she was able to get the car to a parking lot where it evidently healed itself. I met her, traded vehicles, and drove the car home with no issues.


My going theory is that a coolant leak, possibly from the chrome water neck, pooled on the intake, and under braking doused the power steering pulley, causing the less than tight belt to slip. Can anyone think of anything else to check?

Looking under the hood when I met her, and again now that the engine is cooled down, I see:

Antifreeze on the top of the intake.
Some wetness on the power steering pump (not much, really)
Power steering fluid is full, no leaks
Power steering pump belt is snug, but not nearly as guitar-string tight as the alternator belt
Radiator fluid is low, radiator is topped off, but expansion tank nearly dry
Univeral joint (replaced rag joint) is nowhere near any headers, or other obstructions
Engine mounts look okay (no clunking like the failed ones in my 80)
No obvious signs of scraping on the frame where the pulley may have struck it
No notable changes in sounds during the incident, just the wubba-lubba-dub-dub of the low-compression L48 with true duals that drowns out all other noises.
This is a terrible photo. I'll try to take a better one.

Bikespace

Took another test drive. No symptoms, no massive pooling of coolant (but some, see photo). The power steering belt was very taught at the end of the drive. No overheating (checked with an IR thermometer).

Does anyone have anything else to check?

KaelFarmer

Is your wife willing to take you for a drive and try to duplicate the issue at that location? Was she braking hard or only moderately? My car occasionally likes to almost die when under hard braking. If the engine speed drops too fast, the battery light comes on briefly and goes back off as if the alternator stops charging. My power steering belt is removed because the pump seized as a result of system leaks so I can't tell you if the steering in affected when braking hard.

Bikespace

Thanks for the tip! I can give that a try. Knowing that corner, likely only moderate braking, though she then had to brake hard to get around the turn with limited steering. That was part of my test drive, but the 10 miles of highway driving leading up to it were not, so the car may have been hotter than I could reproduce. I haven't seen the engine almost stall durning braking, but it is certainly plausible.

L-46man

Bike space....being as you try so hard to help others...
Here's my take.

Check the power brake booster check valve. Looking at the two 'symptoms' BRAKING and Steering at the same time.
Check Radiator pressure, will it hold?
Bubble check with joy and water 50% thermo housing.
Check pulleys and REMEMBER that the belt runs on it's V not on the bottom....so the belt could be glazed to death and because it's on the tight side, not giving symptoms until under LOAD.
Rough up the P/S pulleys and install new correct belt.
Air bound, air blockage?
Ethylene glycol is a great lubricant!

unkahal

Bikespace

Thanks unkahal! That is exactly the kind of reply I was looking for. That is a great list of things to check.

Braking worked fine, but the check valve is easy to check.
Radiator pressure is clearly down. I have a release-type cap installed. There was no pressure to release when I checked about two hours after shutdown. I ordered a test kit.
Belt is new, but the pulley is original (new pump, though). I'll adjust both, and roughen up the pulley. I have a new belt to try, too.
I got the air out of the PS system the way Borgeson said (run on jackstands, turn the wheel slowly lock to lock a few times).
I need to do a long highway run to see if there is more leaking.

I'll update the post when I get these items checked off. Thanks for the input, and please keep it coming!

L-46man

More things to check;
Kinks in PS hoses and or any leaks in the P/S system that could bleed air back in....doesn't take much.
Rough up the crank pulley too....I just use a nasty wire brush.
Pressure wash the engine...just get all the possible lubes off the front of the engine. This will aid in NEW 'WITNESS MARKS'.
The Thermostat is an easy 15 minute fix to eliminate that.
I thought I saw a 'crack/ scratch' in the upper rad hose....I figure you'd find a split if it was there.
Glazed belts are so intermittent...REALLY check where the belt is RUNNING...the belt should almost be poking out of the pulley sheave....no where near running on the bottom of the pulley.
BIGGIE! check all the P/S pump BOLTS! (the CE had one missing when I got it! As well as a cracked alternator mounting 'fork'.)

Unka

Hope we don't get to the control valve!

Occam's Razor...do the obvious first!

This is a weird one!

BLUE1972

Fix the antifreeze leak, Use a Chevy gasket with the soft ring in the gasket.

That should stop / solve the issue.

Bikespace

Thanks again for all the great advice! I'll update when fix the leak. Hopefully it is just at the waterneck. I need to flush the block at the same time, but I have all the parts.