coolant pressure cap functioning?

[hotrodder]

Just returned from a road trip to Mass and back(250 miles each way. Getting a solid 20 + mpg ( 96 rmw, 3.08, air box, 26.75 dia rear tires. with 450 hyway and 5o local driving)
Found after 200 miles that I had left the recovery coolant cap off the tank and it was resting on the hoses and belts above the water pump. Put it back on and all is well? I think.
Some statistics.. have a 160 thrermostat, Hypertach program, fans on at 175? Engione runs at 1/8th ( first line) on heat gauge.

When I checked for pressure at the cap after running, engine still hot, there seemed to be no pressure under the cap, or maybe minimal pressure. I was expecting a large 'Whoosh" , so It may have been a small, "phift". I'll check again tomorrow when hot and listen carefully for some evidence of pressure.

Could this be the cause of the low temp at the gauge? The readings at both the sites from the AC display board read 160 and 175.

Should I have a large "whosh" at the cap when unscrewed/ and does this lack of pressure indicate that I need a new pressure cap on the coolant tank? No evicence of any coolant leak at all, and no loss of any coolant evidenced

Could this low temp thermostat cause excess fuel being added (due to low temp reported) resulting in lower mpg? I'll have to call Hypertcech as well tomorrow to get some answers.
For all around driving, should I return to the higher temp thermostat and reprogram the fans to higher on/off temp settings?
Thanks for your thoughts

Hotrodder

 

[MrBuick (Magnum)]

Once you are rolling at about 40mph, the fan temp really doesn't matter. The air flow across the radiator will typically do most of the cooling. Running at 1/8 on the gauge, with a 160* stat sounds about right, and is not alarming. If the cooling system is that cool, I don't see that it would really have that much of a pressure build up.

Do yourself a favor, and sell that Hypertech programer, and get yourself a real tune through a mail order place. The Hypertech programer has poven to be a less effective option vs the mail order places. In both power, and fuel economy. The mail order tunes tend to be worth around 1mpg. The hypertech, virtually nothing. If a hypertech tuner will give you 5 hp. A mail order tune will give you 10 hp.

I assume you swapped the rear end out, since a 94-96 Roadmaster never had 3.08's. They were either 2.56 stock, or 2.93 with the towing package.

 

[Inked]

I don't have the towing package but there is an auxilliary cooler in front of the radiator. Oil or tranny?? Stock??

 

[hotrodder]

rear is a 3.08 ( new) with reluctor. Downsized from a 3.74 (?) richmond gears, no reluctor, which netted 18 mpg on the hyway.

To answer the aux cooler, the previous owner added a trans cooler, run in series from both side tanks on the radiator and added in front of the radiator.

If I can ever figure out how to add pictures to the thread, I will post them.

Hotrodder.

 

[Buffman]

left or right side? tranny and stock if so.

 

[hotrodder]

tranny line goes from trans to pass side tank ,crosses to driver side tank, out bottom then to aux cooler , then return to tranny.

Strange???

 

[Buffman]

that's factory IIRC

 

[hotrodder]

thanks for info.

 

[MrBuick (Magnum)]

Stock, it never crossed over to the drivers side for the trans cooler. It went trans, lower radiator on pass side, upper radiator on pass side, trans cooling in front of the rad(near the center is in), out the external trans cooler, and back to the trans. The only way the radiator would even have a tank on the drivers side, was if it was intended for a towing package car. In which case, it would be an engine oil cooler. It sounds like the radiator has been replaced, and the engine oil cooler was use as another cooling device.


To post pictures, you need to host them on Photobucket, imageshack, tiny pic, etc. Then post the IMG link, and the image will show up. You can't directly attach them to the thread. If you can't do this, you can email me the pics, and I will post them.

 

[Buffman]

Cory IIRC that was wagon factory spec

 

[hotrodder]

My gut feeeling is that the trans cooler is an add on. It was attached in front ( drivers side) of the air cond condenser.. This does nt have towing package. Electric fans only!
even if it was original, the lines, ( not labeled for trans fluid) were leaking and had to be replaced. In any case, I moved it several inches forward to assist the a/c in cooling the freon, as I had significantly less cold a/c when in Fl in very hot weather and in idle/traffic. Moving it away from condensor seems to have helped. Will have a/c checked in Fl due to oil leak at o ring (on silver unit/// forgot the name).

BTW.. Hypertech said something to the effect that with the 160 thermostat ...maybe ( very unclear) there was extra fuel delivered due to lower temp thermostat. I'm ambivalent about gooing to 180 thermostat for Fl. driving ( raising engine/rad/ temperature and or gaining better econlmy due to a leaner FI charge at higher (designed) temp. I'm leaning towards staying at 160 thermostat for the winter season in FL. Any suggestions from warm weather drivers?

Thanks for the picture attachment info. Will work up an album and get some pics posted.

Still don't have an answer about the radiator cap... I probably will drive the car to normal temperature and then release the cap and see if there is pressure.

BTW - off thread.. anybody use 89 octane? Can I get away with it in long trip to FL? Not drag racing this week!!!!

Thanks all.
Hotordder.

Will have some comments and pictures of the RAISS system and a modified hood installed in the near future.\

 

[hotrodder]

FWIW - No IIRC build code listed in the spec sheet inside rear tailgate door. In addition, trans lines had cut ends with hose clamps to rubber line, not a factory preped line.

 

[Buffman]

take a picture of the setup. The cooler should be on the pass side of the car if factory. Doesn't matter it if had the tow package, as the stock LT1s had external trans coolers on the pass side of the car.

You'll have more mileage with the 180* T-stat. You can however run more timing with 160* T-stat and make more power. The Hypertech however is a POS and doesn't take that to it's full advantage. Especially since the 160* t-stat and aftermarket tuning usually require one to run 93 octane for max performance.

I'd get a new OEM cap or stant cap. Caps can go bad. There should be some pressure relief after the system has warmed up. Perhaps you have an external leak you're unaware of.

 

[hotrodder]

I think I'll stay with the 160 thermostat for the time being. Runs well, cool, and 20-21 mpg on the road. Changing back to 180 seems to mean reprogramming the fans, and maybe having some detonation problems.
If it ain't broke....

Did the stock setup utilize the drivers side radiator tanks even without an oil cooler line or tow package? If it (96rmw) had an oil cooler as factory setup, where did the oil lines come from. I have not seen any on the engine so far.

Maybe this is a replacement radiator and it was set up to cool the tranny fluid on both sides, as I don't find any oil lines , before they added the aux tranny cooler. Don't know that history of the car.

thanks for the input.
Hotrodder

 

[Buffman]

IIRC the stock setups didn't have the dual tank radiator for coolers unless called for (IE engine oil cooler). If it had engine oil cooler lines they'd come up the driver's side of the engine. Most replacement radiators have both tanks for the oil coolers. I will try to find information about the wagon's using both tanks for the trans

 

[Buffman]

Sounds like the external is an add on:

Not uncommon.
Frank, Reconditioners was that way
Rob Heffernan's cars
A customers 96 RMW , same.
I think John , Striper SS is also.

It is the RPO KNP

The steel cross line is not serviced but if your parts guy looked at the lower line, the KNP option line 10270307 is a different part number than all the others (10270308)

KNP is listed as Cooling system , transmission, heavy duty.

Not to be confused with KD1 Cooling system, transmission , oil which is the front external right side air to oil trans cooler option

This is my first LR head scratcher and I've come to the place where I know an LR Pro might know. Have I an odd configuration? 95 Black LR w/ LT1 to be specfic; car from Ruphy.

1 - Engine has NO oil cooling; no adapter at the filter pad and no lines running forward to the drivers side radiator end tank.

2 - Both end tanks - driver and passenger sides - are used for transmission cooling - with apparently 3 OEM fluid lines.

3 - Both lines coming from the transmission are steel; just forward of the idler pulley both steel lines change to short crimped hose sections which are again attached to steel lines for connections at the end tanks.

4 - Pressure line from trans leads to the lower drivers end tank. This line is 'one' assembly of three.

5 - A drivers upper side to passenger lower side rigid line attaches the two end tanks to one another; it's routed down the drivers tank to the bottom of the radiator and then bends 90 degrees to go over to the lower passenger side end tank where it connects to the tank. This rigid line is the 'second' assembly of three.

6 - Rigid fluid return line from the upper passengers side tank is routed down, converts to rubber hose and like the pressure line goes back to steel line below the idler pulley. This line then runs back all the way to the transmission. This is the 'third' assembly of three.

7 - The whole enchilada: Pressure line from tranny to drivers tank, rigid transfer line from drivers to passengers tank, then return line from passenger tank to trans. 3 pieces total.

8 - The car has dual electric fans.

9 - The car has no externally mounted auxiliary cooler of any type.

10 - The best part - and I guess this depends on how one looks at this - the above has stumped two PRO's. One is a well known community hero, the other is a local experienced GM Parts Dealer; a mini-Dal if you will. Parts man could not find this configuration in any of his resources based on my VIN Build Sheet Data, nor could 3 of his line mechanics recall this config.

Gentlemen of the LongeSSt Roof variety: what have I got? Is this a normal OEM config or option? Note: My 95 FSM set does not reflect this config either.

All the above started with a pissing fluid leak the other day after sitting for months; leaving a trail out of the garage and then a puddle. Pin hole leak in the pressure line from the tranny where the tube enters the 'long length' attachment nut to the lower drivers end tank.

These 'long' nuts were NY Winter Rusted BIGTIME ref pinhole. In short, I managed to get both lower nuts out of the end tanks [both tubes were rusted solid to the nuts and neither nut wanted to let go of the end tank]; these sections of tube were pure rust. Successfully removed and drilled out the nuts without damaging their interiors. With 3/8" copper tubing and a couple compression fittings and unions, I slapped a couple double flares on short copper sections to reside in the OEM tank nuts, and then attached the copper tubes with compression fittings to the OEM steel tubes.

Back in business. Ops check good/no leaks. About $10 of materials. Anyone priced a set of trans cooler lines lately? cough cough hack hack Elizabeth it's the ..... MEDIC!!!!

So...... the stumped community hero will rename maneless and therefore, I have come to the Long Roof Lords with arms out and palms up begging for an education.

Now, time to go back and cross T's and dot I's.... yeah, it reads ok. Windy - but specific.

 

[hotrodder]

ah ha!
Buffman, MANY Thanks!
Looks like, on first glance I have the above referenced system with an additional trans cooler.

RPO has a KNP indicated.
A quick recall of the layout of the lines on my system ( too dark and cold out now to look... will do tomorrow to confirm) seems to be described above. Only change is the addition of an external cooler spliced into one of the two lines crossing under the crank pulley and also into the upper steel hose from ( into?) the upper drivers side tank.
Certainly no 'Short crimped factory hose", but hose clamps and barbed fittings on the cooler, and (now) Trans Cooler 3/8 oil lines.

Now that I know the routing configuration and which line is coming and going . Will confirm routing tomorrow.

Hotrodder