Baffling B&B cooler problem

[Formerly Steve Wilkinson]

I have a 24" center-mount B&B oil cooler that simply won't flow oil on my 911SC. B&B has checked it out and says it flows oil just fine. I put it on the kitchen counter and pour a big teapot full of boiling water into the upper fitting and it indeed flows just fine--comes out the bottom fitting and the entire cooler gets hot to the touch, particularly the end opposite the inlet and outlet fittings, which is obviously where the cooling tubes terminate.

Put it on the car and run it until I get an indicated oil temp of 200 degrees. Get out and feel the Aeroquip hoses and they're both hot, so obviously the thermostat is working fine. Feel the cooler and the only part that's hot is the little "tank" to which the inlet and outlet fittings are attached. The fins are cool the whole way across the cooler, and the far end of the cooler is literally cold.

Let the car idle for 15 minutes, zero airflow across the cooler, still cold. Crack the top fitting until oil comes out, let it flow for a minute in hopes that this will vent any air blockage, still no change.

The only thing I can think of doing at this point is drilling and tapping a hole in the top of the cooler, at the far end, and installing a plug, back the plug out slightly and see if that vents any mysterious air blockage.

Anybody got any better ideas?

Stephan

[Chuck Moreland]

I recall your post awhile back when you said you had a B&B missing a block off plate between the fittings. Is this the same cooler or did they send a replacement?

[Formerly Steve Wilkinson]

I'd assumed that was the problem originally, because a reasonably knowledgeable racecar tech told me B&B had welded some coolers up with the baffle missing, but I was surprised to find (with a bent wire) that the baffle was properly in place, wehn I took the cooler off the car. I sent it off to B&B anyway, because they did say (to Steve Weiner) that they'd had a few problems with a few coolers recently. It tested just fine and they sent it back.

Steve Weiner is currently theorizing that at the speeds I'm running the car on the road--i.e. just hard enough to get the oil good and warm on a 90-degree day--I'm really not putting enough revs into it the build up the pressure and flow to fill the cooler.

Stephan

[chrisp]

Could the water test be masking something? Meaning, that water flows OK but oil may not due to much greater viscosity.

I noticed on my recent install that once the thermo opens a wet cooler will begin to steam. Maybe you can build this into your test.

Perhaps under idle there's not enough flow to push oil through the entire cooler since it goes in the inlet and trickles down the tubes/fins to the lower tank and out the fitting. If the oil is just trickling in then it will flow down the first tubes/fins and not reach those at the opposite end of the cooler. Could there be a problem with your thermo not opening all the way and thus not flowing enough oil?

In my car when I come in from a run and I am sitting idling I can hear the oil rushing through the outside lines.

[Chuck Moreland]

The wire test is a good. Maybe also shine a light into one fitting, then see if any is visible looking into the other fitting - on the theory the baffle may have a hole that you didn't find with the wire?

Steve may be onto something with pressure. How about giving it a real workout, get it good and hot and drive it hard.

The part that I find perplexing is the far end is cold while the fittings are hot!!!

Air flows through the cooler all the time so I wouldn't worry about a pocket or bubble. The scavenge pump is overdriven about 25% compared to the pressure pump, so it is pumping at least 25% air at any given time.

[Formerly Steve Wilkinson]

Chrisp, the flow in a B&B cooler is entirely horizontal, from one end to the other. There's no way for oil to "trickle down." If oil is getting into the cooler body, it has to go all the way to the far-end tank (there's no such thing as a "lower tank" and then back through another set of horizontal tubes to the outflow fitting.

Chuck, I just took the car out for half an hour of hard running, ambient temp a humid, sweat 85. Did about 15 miles at 100--we have a very convenient road from Nowhere to Nowhere that I use for such activities--plus a fair amount of 5,000-rpm fourth-gear running and a nearly-full-throttle run up the long, steep, two-mile climb up Storm King Mountain, where we live.

Bad news is the cooler feels just as cool as it ever did.

Good news is I couldn't get the oil temp above 195.

Stephan

[Formerly Steve Wilkinson]

By the way, if there's anybody out there with a 24" B&B center-mount cooler who can tell me what it feels like to the touch after relatively normal but vigorous road running (not racing) on an 85-degree day, do tell.

Stephan

[sammyg2]

You have the oil going in the bottom and out the top of the cooler, right?
If so you don't have to worry about venting, it will automatically fill/vent.
As fas as how it's staying cool, I don't have a clue. Maybe the darned thing is just too efficient?

[Formerly Steve Wilkinson]

I've tried it both ways, but yes, the inflow is currently at the bottom fitting, outflow at the top (confirmed by the fact that the top hose is tangibly though slightly cooler to the touch).

Stephan

[304065]

Here is a picture from their catalog to make it easier to visualize the inlet/ outlet layout.



Stephan, how about borrowing a trick from the aircraft world-- put a few layers of duct tape across the front of the cooler and drive until the oil temperature stabilizes. Then pull over, jump out and rip the tape off, and watch for a temperature change.

If the oil is entering the end tank and going right back out the other end, airflow through the cooler shouldn't make a difference to the oil temperature (except the limited flow that reaches the end tank and lines, if they are in the slipstream.

By the way, I found the "baffling" pun to be excellent.

[Formerly Steve Wilkinson]

Wish I could take credit for the pun...entirely unintentional,as I suspect you knew!

Anyway, I'll try the duct tape deal.

Stephan

[chrisp]

Hot in the top. Cold out the bottom. It wants to sink as it cools.

[sammyg2]

Chrisp, with a standard thermo-syphon design that would be correct, but this isn't that type of design.
This is a pressurized system with a substantial rate of flow so if you go in the bottom the exchanger will fill from the bottom and push the air up and out, eventually becoming completely full and air-free.
If you go in the top and out the bottom the entrapped air bubbles will gurgle back up against flow and may never be completely vented. Not that big of a deal except it would effectively reduce the cooling capacity.

A standard water cooled engine works that way (in the bottom out the top), but they screwed the pooch and went backwards with the radiator for convinience and packaging. That's part of the reason they have a fairly large tank across the top of the radiator, so the air has somewhere to go.
If you took a standard 'merican water cooled V8 car and reversed the flow through the radiator it would increase the cooling capacity and efficiency.

[Formerly Steve Wilkinson]

I've tried it both ways. It shouldn't make a bit of difference whether the oil wants to sink or you force it to rise. It's in and out of there pretty quickly.

Stephan

[dad911]

Stephen, I used to run this cooler in a 3.6 conversion. 2300 lb car, front oil tank, no thermostat, track use only. In all but the hottest summer days, I used to block off some of the air ducted to the cooler, or the oil would not reach operating temps.

[Formerly Steve Wilkinson]

Okay, I'm slowly becoming convinced that the cooler is working all too well, in part because I have one of Chuck Moreland's cooler-air exhaust ducts (below the car) behind it...

Stephan

[chrisp]

FYI, in similar conditions on track my Mocal 44 row (13"L x 6"H x 1.75"D) keeps my oil at 200-210. You have 120% more cooling volume and 70% more frontal area.

Your point about it working really, really well may be spot on but the cooler should be at least as warm as the return line.

[Chuck Moreland]

Originally posted by Formerly Steve Wilkinson
Okay, I'm slowly becoming convinced that the cooler is working all too well, in part because I have one of Chuck Moreland's cooler-air exhaust ducts (below the car) behind it...

Stephan

Well, you haven't seen elevated oil temps. That says alot and maybe everything is working as planned.

The part that doesn't jive is the return line is warm, but the opposite end tank is stone cold. That tank should be at least as warm as the return line.

[Formerly Steve Wilkinson]

Cramer's a freakin' genius. I did as he proposed--duct-taped the cooler so no air could get through it--and after a 30 minute drive, the oil temps were 15 degrees higher, and better yet, the entire cooler was hot to the touch. Thank you, John!

Stephan

[304065]

Glad I could help! Maybe I could get you to sign my copy of "The Gold-Plated Porsche?"