Long story short, my lower radiator hose slipped off the radiator.

Backstory, replaced the cap about two weeks ago, then the heater control valve comes apart. Replace it, refill and bleed, all good for about a week. Don't drive the car at all this week.

Today, the lower hose comes off at a stop light. This was about two miles from home. I nurse the car home. When I get about a half mile from home, the temps really start shooting up, check gauges, all of that. Temp topped out about 262 when I pulled into the spot.

The oil was heating up pretty good, not quite into the "red" on the gauge. Heard pinging sound as I got real close to home, kept rpms as low as possible. But when i lifted the hood to see what happened, there was some smoke and could smell burnt oil.

I'm praying the heads didn't warp of course, or the bearings didn't fry.

I'm wondering now if the cap I got isn't releasing pressure in the system, and this is causing these parts to blow apart?

The radiator is about three, maybe four years old, GM replacement. The cooling system has been fine up until now.

So, what are the chances that the engine isn't hurt? And does anyone know a part number so I can get a new cap from GM?

 

Any cap will suffice, as long as it is the correct pressure (16# ?).
Most caps are made by STANT, including those under the ACDelco brand.

According to STANT reps, all caps made now are designed for both open and closed systems, but just make sure when buy a new cap
that the cap is for a 'closed' system.

 

My 94 has seen 260° coolant temps a couple of times without issue. Hope the same for yours.

 

I'm hoping it's okay. It didn't really start getting up there until the last little bit. I'm just worried because I know by the time I got there, most of the coolant was obviously gone, and the engine was pinging pretty good. That and the oil temps were up there.

I know it's due for a rebuild at 160K although the crank and bearings are about 65K right now. Just no money in the till for it right now.

I knew I should have sold it before I moved down here.

Frist things first though. Going to go ahead and get a new lower hose and put it on, fill it up, change the oil, and see what's up. Good or bad, probably sell it as is, being perfectly honest with any potential buyers of course.

 

If you got other cooling system pcs blowing/leaking you may have cyl pressure building up in your system. Hope its not the case but sounds like it. Surprised the seal on the WP hasnt gone yet. I had the same thing on an L98 happen with the lower hose blowing off. Didnt get hot ran fine, parked the car got out and boom!
Hope its something minor for your sake!

 

Yeah, I don't know at this point. There hasn't been anything that would indicate a head gasket, or such issue that would leak combustion into the cooling system. Temps have been normal, starting hot or cold has been solid. No sign of power loss, or reduction in MPG's. No white smoke or black stuff in coolant, or coolant in oil.

It could all be coincidence. I do know that just prior to the hose coming off I pulled into a parking lot that had steep incline, maybe that knocked the hose loose? Can't say for sure.

Maybe she knows I've been looking at trading my Caddy for a C5 or C6, and she's being a jealous you know what. lol

 

What is the pressure rating on the cap? I would check that it isn't of a higher rating than the OEM. If it's the same or close you may have issue but again it could have been an old hose giving up the ghost. I hope it's alright for you!

 

It's for a 16lb system, I believe that's correct?

I haven't really had a chance to make a real close inspection. The hose is old, but didn't bust or show any signs of damage.

My major concern is the effect it may have had on the engine. But I guess I won't really know that until I get it started.

If it is damaged, the question then becomes, rebuild, LSx swap, or sell cheap be Vetteless, and learn to live like a 'normal' person. lol

 

Alright, the new hose is on. Filled the system. To do this, since it was virually empty, I opened the bleeder screw to help let air out as coolant went in. Filled until I saw coolant coming from the screw, tightened, and continued to add coolant until it just below the ring on the surge tank. Made sure the overflow tank was at the cold level. All done, about 3 gal of 50/50.

Before starting, I bumped it a couple of times just to make sure nothing was seized, on the third bump, it fired right up. Let it idle through open loop. With the cap off, I watched the level, and revved a coulpe of times. Reving saw the level increase. There were 'burps' of bubbles from time to time, but nothing of a rythmic or consistant nature. The engine itself made no strange noises, no knocking, just the usual rocker tick. Throttle response was solid, no misfires or hesitations, no MIL.

Now, when the temp hit 230, and fans came on, instead of going right down as usual, it hovered right there, go down to 228 or so, up to 236 (Highest) but for the most part at 230. Let it idle there for a good five minutes or so, and that's where it stayed. When I turned it off, I could hear coolant redirecting itself everywhere, and the overflow tank was near the top.

I'm sure there is still some air in the system, so I'm not freaking out about it not cooling down right away.

So, if were bleeding compression into the system, would it have shown up at that point, or did it, and i just don't recognize it?

I've replaced the t-stat, the radiator, the upper rad hose, the heater valve (twice now) and now the lower hose, and have seen those 'burps' each time I filled the system.

 

New oil?

 

Last change has about 3K on it now, so it's due. I also have a slight leak on the timing cover, so it gets a quart or so between changes.

Also it seems that my analoge sensor is toast, needle just sits. Took it to the store, just down the street. Let it idle a bit in the parking lot, hit 240 before I shut it down. On the way home, stayed around 230, but the low coolant light came on for a second when I accelerated, then went off.

But the good news to me is that there doesn't appear to be internal engine damage, thus far.

 

Ran a chemical block test, and it tested negative for combustion gasses in the coolant system, stayed blue.

So what is the effect of the analog temp sensor not working at all? After a few cycles, the needle doesn't move.

I know the fans are controlled by the digital sensor on the pump, and they come on. So, I'm not real clear on the analog sensor on the head, does it effect ecm operation, or simply read the gauge?

 

I finally broke out the FSM to learn a little more about why my analog gauge isn't working. I thought the thing that looks like a coolant sensor on the passenger side head was the one that feeds the gauge. However, there is not one single mention of it anywhere in the FSM. It only mentions the temp sensor on the water pump.

So, then what is that sensor on the side of the head?

 

The temperature senders sole purpose in the passenger side head is to feed a temp reading to the analog gauge. Nothing more, does not feed any Fuel/Timing info to the PCM. It is a single wire connector. I just replaced mine on Thursday actually. Advanced auto has it, part # WT3025P, its a BWD brand. Put a little thread sealant on it before you thread it in. Coolant will come billowing out when you remove the old so be prepared to catch it. I believe I used a 13/16" deep well socket to remove the old and install the new. Once you get the new sensor in spray the spark plug wires and any other electrical wires with some fast drying electrical contact cleaner. Good to go!

Keep in mind, the sensor in the water pump is actually a "Coolant Temp Sensor", as it feeds info to the PCM. The one in the passenger side cylinder head is a "Coolant Temp Sender". They both have different purposes. I believe the F-bodies have the cylinder head sender in the driver side head.

 

Thanks Torch, that's what I thought. I just thought it was strange that there is absolutely no mention of this sensor anywhere in the FSM.

 

I couldn't find any mention of it in my 94' FSM either. But then again, a lot of things are hard to find in there. GM did a great job of making it time consuming to navigate. I just wanted to find a part# for it. Ended up finding a nice list of LT1 part #'s on an F-Body forum.

 

The '96 FSM has a complete list of all the engine control parts and it's location. ECT is only mentioned at the water pump.