Where is the Coolant going

[Uhrlto]

this is beginning to turn into a game of hide and seek and not a particularly fun one. Okay, parameters first, 1992 Fleetwood pace arrow, I think it's often referred to as a P 30. Chevy 454 V8, 52,000 miles. Initially when we bought our rig, it was overheating on the short drive to our home and since it was hot I waited for the following day to check the coolant level. To my surprise it was practically empty. I filled it with about one and three-quarter gallons of a 50-50 mix. After that it seemed to run very cool temperature climbed slightly as expected, when we were climbing a hill but it rapidly went back down. Okay let's take you about a month later, we take the rig out for a shakedown cruise about 15 miles from our home to a KOA. Everything was fine, everything worked beautifully. We came home after a successful weekend parked our motorhome back up in the storage facility and left it there for about a month and a half. Okay so now I bring you to today we decide to take a three-day weekend so I go and get the rig and I'm noticing that it's overheating, so I let it cool down and again I'm filling it with about a gallon and a half of coolant. I cannot see a drop of coolant leakage anywhere. The reserve tank has fluid in it. The temperature averages around 210 to 220 Street driving. Important fact to note that when I was coming downhill on the freeway the temperature dropped very low on the temp gauge probably down to about 162 175. But then rapidly rose again when it was under acceleration.
Okay, there's all the details, I have checked to see if there is exhaust fumes in the coolant and there are none. The fans are working as best I can tell, that means the electric and mechanical. Where is the coolant going. This is starting to drive me nuts. I also can't be sure about the temperature situation because I've read several different posts that a 454 can run anywhere normally from 192 to 220 depending on the situation, whether, and terrain. If anybody has an idea as to what I'm dealing with I would sure love to hear your input. We are going to attempt to get out of our Valley tomorrow and go for another three day weekend but I have the early morning to work on anything that might need to be repaired.
Once again my deepest thanks to everyone for their input.

[TeJay]

I'll give you what I know concerning these type of issues. Most of these systems are about the same. What plagues one plagues most and the causes of overheating are for the most part universal.

First of all you need to verify if you are actually having overheating issues. Maybe it's a defective temp sensor. You mentioned that at one time the temp went way low then came back up. That tells me maybe something is not reading the temps correctly.

I'd get an infrared temp gauge and when it's showing hot take some reading around the radiator and if possible at the thermostat housing. Compare with what you are seeing on your gauge and go from there. You have to make sure you are not chasing your tail.

Once you verify that you do have a temp problem sometimes a thermostat can and will operate intermittently. It's easy enough to change one.

The next thing I'd do is find a place that will pressurize your system with 15 lbs of pressure. Most all systems that I've worked on will pressurize the system to 15 lbs. This raises the boiling point of the coolant 3.25 degrees for every lb above sea level or about 48 degrees above boiling. Changing the cap is not an expensive thing to do either.

In recent years many systems use a pressurized overflow tank. I don't know what the P-30 has so I can't advise. If you have the pressurized over flow tank it's not a lot different except the tank cover acts like a radiator cap.

If all of that checks out and you are still loosing coolant, really do have a heating issue and not seeing any external leaks the coolant can be escaping through a crack in a head and being sucked into the combustion chamber and burned along with the air fuel mixture. That is not a good thing.

I have sealed cracks in head using radiator sealants but for a MH that you expect to run and run that's not a good reliable long term fix.

You've got some things to look for and I'm sure some P-30 owners will weight in on this issue.

TeJay

[Uhrlto]

Thanks Tejay, I do appreciate the reply. I'm pretty sure I can eliminate a head gasket or a cracked head, yes the mere thought makes me tremble. I have had a vehicle that had a cracked head and you can usually smell coolant cooking. It has a distinct sweet smell, and I'm not smelling a thing.

I am, like you hoping its just a defective thermostat, I can change that very quickly. I do not have a pressurized recovery system, just a bottle and hose. I have already replaced the radiator cap with a new stant, with a lever.

How about timing, with the engine running as smooth as it does, I dont consider it, but if its too far advanced that could cause a problem, could it not? As you can see I'm beating my head against a wall.

Tony

[DeOrellana]

Sorry for the long post and if I'm stating the obvious, just trying to be methodical.

I think the most important thing to identify is where the coolant is going, as per your thread title. Coolant can go three places. Internally into the engine (bad), external leak such as hose or radiator leak, or vented out through the radiator cap from over heating.

From your description it does sound like you've ruled out external leak. We'll assume for the time being that it is not leaking internally. Without doing a compression check or radiator pressure check you can't be sure, but the indications are that it is not. So we will assume the engine is over heating and the coolant is escaping in the form of steam.

I would also rule out the temp gauge and sensor as the only problem since the loss of coolant shows that there is an actual problem. Yes, the sensor may be bad, but from your description I doubt it.

Since the engine temperature drops when you are on the freeway, I would rule out the thermostat as the culprit. Could be partially stuck and restricting coolant flow. It's cheap and as you say easy to remove, and it never hurts to have a newer trustworthy thermostat. Cheap insurance, especially if you don't know the condition of the rest of the cooling system.

if your P30 is anything like mine, driving up hills puts a high RPM load on the engine and not much air flow through the radiator, while driving on the freeway gives you much better airflow through the radiator. So I would focus on the radiator's cooling capacity.

Take a look at the coolant. Is it staying clear (clean) or does it contain brown sludge? If it contains sludge, I would start with flushing the cooling system. The radiator may be blocked, and the IR thermometer as TeJay described is an excellent tool for determining if the radiator is blocked. The radiator should have roughly the same temperature vertically with the temperature dropping from inlet side (from thermostat) to outlet side. Also check for debris blocking the airflow through the radiator. The A/C condensor is usually mounted in front of the radiator with electric fans. Check the condensor for debris also.

If the radiator is not blocked, not sludged up, and air flows through it, then the only thing left are the fans. If the A/C is on and the fans are not turning, then that might cause your problem, but with your symptoms I don't think they would affect it that much. So you are left with the engine mounted cooling fan.

The engine mounted fan is mounted on a fan clutch. The fan clutch is temperature sensitive and changes how much it pulls the fan depending on the temperature of the air flowing past it. Basically, if the air flowing through the radiator is hot, the clutch engages and if the air is cool, it disengages. If the fan clutch isn't engaging, it will cause the symptoms you are describing - overheating on hills, and cool running on freeways.

Finally, the timing may be an issue. I worked on a '69 Firebird with a built Pontiac 400 where it would overheat at idle if the timing was set to the recommended settings. It ran just find, would just overheat. Advancing the timing helped cool it down. With a stock 454 I would check the timing and the timing advance mechanism and vacuum to make sure it isn't sticking as part of your basic "getting it back in shape" routine, but since you say it is running smooth I wouldn't think that was the culprit.

My money is on the fan clutch.

[twinboat]

#1, Borrow a pressure tester, I believe auto parts store lend them out. See if it holds pressure and look for leaks.

#2, look at the thermostat housing bolts. If they look like they've been out, the PO may have pulled the thermostat out, the old school, wrong thing to do. May not fix it but could be the reason for the temp swings.

#3, check the fan clutch for any signs of leaking fluid near the hub.

Good luck.

[DeOrellana]

Originally Posted by twinboat

#1, Borrow a pressure tester, I believe auto parts store lend them out. See if it holds pressure and look for leaks.

#2, look at the thermostat housing bolts. If they look like they've been out, the PO may have pulled the thermostat out, the old school, wrong thing to do. May not fix it but could be the reason for the temp swings.

#3, check the fan clutch for any signs of leaking fluid near the hub.

Good luck.

Good point about the PO pulling the thermostat out. Forgot about that one

[TQ60]

Fist things first..cheap and easy ones!

Take the cap to auto - zone or any place that advertises that they loan out special tools.

Have them test. The cap, often a tool by Stant which is a simple hand pump is used.

Ask to borrow it to check your system.

Lots of times the cap will under - rate meaning a 16 lb rated unit will vent at say 5.

Water boils at 212 @ sea lever and it rises 3 degrees mer pound psi so sealing required for modern engines to keep water as water.

Inspect the top seal as that keeps the water inside the system.

Next triple check the over - flow recovery tank by filling completely with water then with compresses air and very low pressure and holding hand over fill port check for leaks.

Our jeep started doing same thing and a 93 cherokee has cross flow radiator with fill port not perfect spot.

The cap valve would open at almost nothing allowing any expansion water to quickly escape and for it to boil at lower temp making it worse...not sure if actually boiled.

Combine that with a small crack about mid way up side of recovery tank it looked like it was doing its job but would loose water.

The top seal in the cap also leaked so the cooling engine would not draw water back...but the level in recovery would go down so it looked like it was all good.

Dug out the tester and discovered bad cap then tested tank and now all replaced and good.

Jeep only has 450 k miles so I guess it needed spmething...

Timing is computer controlled so pause on that.

When pressure testing engine look close at water pump was often a bearing seal will fail but only leak when warm and under pressure.

[Uhrlto]

First of all my thanks to everyone that offered a reply for this problem. Let me add now what happened today.
Ok I started this morning 17th at 8 am. My first hope was that the radiator would be empty, however it was full, however the recovery tank was fully empty, and I had filled it the night before, so all that fluid was sucked into the radiator as it cooled. So I started on the engine by replacing the plugs which were totally shot, All had gaps way over the 035 that it was supposed to have. two of the plugs were fouled, and 2 were put in by Hinjo the Sumo wrestler. I broke one getting it out. The distributor cap was cracked slightly and the rotor was black with carbon tracing, all replaced. The thermostat was old and I replaced it with a new 195 degree stat and new gaskets. Refilled the radiator to full, replaced the overflow tank which had a small crack, dont know if this was my leak spot. Replaced the radiator cap with a new stant lever type cap.
So when I started it it ran smoothly like I suspected, and I warmed it up a bit then shut off and topped off the radiator. re-started the engine and l let it get to 195 which it did quickly.
I drove it from Reno, nv to our campground in Cisco Grove, Ca about 45 miles and all uphill on hwy 80, the temp gauge got up to 225 degrees, my speed got as low as 40 mph but as high as 65, and she made the climb and did not boil over, of course I did keep the AC off. On the down hill side it quickly returned to 195 degrees. So is it fixed, I dont know. I do know I got a check engine light a couple of times on the run up hill, and dont have a clue as to why. So thats the new wrinkle now a check engine light.

Tony

[TQ60]

Cracked over flow will cause coolant loss as the radiator is not designed to have air space above water for expansion.

So water goes into tank and leaks.

Engine cools and draws air in.

As water flows in system it continues to blow out water.

You can get the cheapest reader you can find just to read any codes.

Maybe a wire not connected or maybe you had some air in the system still.

No reader then stop by auto zone as they read for free.

They also sometimes have cheap readers...Ours was maybe 17 bucks on clearance.

[CJ7365]

here is a you tube vid on how to get the code for an OBD I system on a Chevy


Looks like you fixed your coolant issue, good job, bet it runs a lot better with new plugs etc.....

https://www.youtube.com/watch?v=V8nZpQyoRh4

[TQ60]

Sorry...overlooked the year...OBD1 era...which is okay.

Did not watch video but most involve shorting out a couple pins in the connector then counting light flashes.

Just be sure you have correct pins.

[mchero]

This caught my eye;

Originally Posted by Uhrlto

I have already replaced the radiator cap with a new stant, with a lever.

Tony

If the rig has a coolant recovery bottle you have the wrong radiator cap. That Stant with a lever is not a coolant recovery cap.

Those lever type caps can suck air around that lever.

Don't think it's the main culprit but worth looking into.

Keep us posted, interesting thread!

[Uhrlto]

Looks like you fixed your coolant issue, good job, bet it runs a lot better with new plugs etc.....

it ran great with the new plugs, a lot more power

https://www.youtube.com/watch?v=V8nZpQyoRh4

[/QUOTE]

[TQ60]

Originally Posted by mchero

This caught my eye;



If the rig has a coolant recovery bottle you have the wrong radiator cap. That Stant with a lever is not a coolant recovery cap.

Those lever type caps can suck air around that lever.

Don't think it's the main culprit but worth looking into.

Keep us posted, interesting thread!

They do have lever caps for coolant recover type.