Bad coolant sensor

01yellercobra · Mar 26, 2019

My son attempted a PI manifold swap the last couple days that ended with figuring out the manifold was a POS. So we threw the original manifold back on. When we started it the engine sounded like it has a cam. I pulled the codes and one was P0117 I think. Coolant sensor circuit low or something to that affect. I noticed the fan kicks on a few seconds after starting the engine. Would a bad sensor cause a crappy idle? If so any way to figure out which one it is?

Silver95bird · Mar 26, 2019

I think that's the passenger side one, sounds like it's either disconnected or broken. I had one crack at the base and corrode inside where I couldn't see it... It gave me fits until I decided to replace it and it snapped in half disconnecting it. The other one works the gauge, so if you get the wrong one the dash would show it.

01yellercobra · Mar 26, 2019

Thanks. We got the old intake back on about 10:30 last night just to have it idling like that. I imagine being so old and swapping between manifolds might have finished the sensor off.

01yellercobra · Mar 27, 2019

Does anyone happen to know the resistance range of the sensor and the switch? I checked the sensor yesterday and it was showing 30k ohms with the car at ambient temp.

Things got "interesting" yesterday. I tried to look at it while my son was at work. I checked the coolant sensor and saw the resistance. Just for S&G I decided to crank it over to see what would happen. My son said he tried to start it that morning but it would spin then stop. So we both assumed low battery since it's been cranking a lot lately with not a lot of charging time. He threw it on the tender and left it. Well, I turn the key and it spins then stops. But it sounded like a low battery to me. So I hit the key again and it spun and fired up. Then I heard a clang. Almost like when a fan throws a tool we've forgotten about. So I shut it down and proceed to pull plugs. All the plugs on the drivers side are fine. I pull 1 and 2 and the electrodes are wet on both plugs. When the wife gets home I have her watch the plugs holes while I crank it. I put the gas pedal on the floor and turn it over. After a few spins there's a loud bang again. We both kinda stare at it and at this point I'm not sure what to do/think. After my son gets home we talk about possibilities and options moving forward in worst case scenario. At this point I think the engine is hurt. I spin the engine over by hand and nothing sounds out of whack. It's pretty easy to spin with 6 plugs pulled out. I spin it with the starter again we hear kind of a thumbing noise. At that point we went inside.

So I was talking to a buddy today and he says he can't see it being that hurt. Which I tend to agree. Something that occurred to me is when I was spinning it while the wife was watching was that the coil packs were still hooked up. What I'm wondering is if the injectors didn't shut off like I thought they would when I held the pedal to the floor and the loud bang was the fuel igniting in the two cylinders. When I spun it with my son I had disconnected the coil packs just to be safe.

My son works Saturday so the plan is to get a bore scope from my buddy and scope all of the cylinders. From there I'll either do a compression or leak down test. If those turn out good I'll move forward. It's bugging me that it can't be dead yet. I know a lot of people are going to say he needs to learn and figure it out. But there are times dad needs to step in and see what's going on, then explain what happened.

07GtS197 · Mar 27, 2019

Its possible that its igniting but I wouldnt think its likely. Have you tried whacking the starter then trying to start it again? I find it off that all this happened after an intake manifold swap. Is the coolant topped off and air pockets? Perhaps something was dropped into an intake port while swapping intakes?

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01yellercobra · Mar 27, 2019

07GtS197 said:
Its possible that its igniting but I wouldnt think its likely. Have you tried whacking the starter then trying to start it again? I find it off that all this happened after an intake manifold swap. Is the coolant topped off and air pockets? Perhaps something was dropped into an intake port while swapping intakes?

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That's how I feel too. We topped of the reservoir the night before, but the next morning it was dry. That's why I'm going to look it over Saturday. I need to be able to look at it without having to talk to him at the same time.

01yellercobra · Mar 30, 2019

Well, somehow an intake swap lead to a busted engine. Number 1 connecting rod is definitely broken. I was able to push the piston down with a screwdriver through the spark plug hole. So now we start looking at swapping the PI engine sitting on the stand.

ttocs · Mar 30, 2019

wow I thought I had the most unsuccessful intake swap when one of the bolts holding the intake to the head broke when I was taking it apart. Ended up with new heads after that as it was just a rusted mess. Did some coolant or something get down into the cylinder or how would you break the connecting rod?

01yellercobra · Mar 30, 2019

I think it was a series of errors on both of our parts. It was sucking coolant into the intake ports with the crappy PI intake installed. I would say it must've had coolant left over from that, but after we put the NPI intake back it fired up and idled. Not very well, but it idled. Although when I finally pulled plugs 1 and 2 both were wet. But I don't know where the coolant came from in that instance. So really, I can't pinpoint one step that caused it all.

At this point we're going to inspect the spare engine he has. Hopefully the coolant passages aren't filled with rust. He will need a new intake no matter what. But that's cheaper than a new engine.

The bright side is this gave me an excuse to buy one of those vacuum systems for filling the cooling system. I've only used it to test for leaks but I like it so far.

07GtS197 · Mar 30, 2019

Are you sure the rod is busted? Even at idle speed there would be a nasty knock and the piston would be at the bottom of the bore probably. You could be right but I just dont see how that couldve happened. Even if coolant got into the cylinders it wouldve hydrolocked the motor or busted a ringland before a rod wouldve broken.

If you already have another motor then by all means swap it in but Im still skeptical of the issue.

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ttocs · Mar 30, 2019

I have to agree. I would take the heads off and get a real look at whats going on

01yellercobra · Mar 30, 2019

07GtS197 said:
Are you sure the rod is busted? Even at idle speed there would be a nasty knock and the piston would be at the bottom of the bore probably. You could be right but I just dont see how that couldve happened. Even if coolant got into the cylinders it wouldve hydrolocked the motor or busted a ringland before a rod wouldve broken.

If you already have another motor then by all means swap it in but Im still skeptical of the issue.

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ttocs said:
I have to agree. I would take the heads off and get a real look at whats going on

I put a rod in the spark plug hole and spun the engine by hand. It never moved. So I took a long skinny screwdriver and put it through the hole. When I felt it touch the top of the piston I pushed down and the piston slid down the cylinder. So I'd say the connecting rod is no longer holding the piston in place.

We had the engine idling Monday night about 10:30. Nothing broke until Tuesday evening. So between Monday and Tuesday coolant filled the cylinder.

01yellercobra · Apr 2, 2019

So the hits keep coming. Saturday night after my son got off work we decided to do some checking on the spare engine. We pulled the pan and found some crud in the bottom of the pan. It was a mix of sludge, water, and metal. There was also a piece of plastic sitting on one of the chains since we had the engine upside down. I managed to fish the plastic out and it looks like one of the tabs for the timing chain guides. I saw another piece tucked further down the timing cover that I couldn't get to.

My son pointed out the metal flakes stuck in the oil pump pick up as well. We decided to pull one of the rod caps just to check it out. The bearing was tore up from lack of oil or something. The crank seemed ok, but the bearing was definitely shot. So between that, the bad intake, and all the rust in the water jackets we decided to shelf that idea. Since time is of the essence on this car we decided to order an engine from MPS. It should be here next week. We found an engine out of a 2003 with only 76k on it.

delling3 · Apr 3, 2019

So, sorry to hear things went sideways. I am getting ready to do a intake swap myself, and was curious about your comments about the intake being a POS. Was this a OEM intake? What about it was bad?

01yellercobra · Apr 3, 2019

delling3 said:
So, sorry to hear things went sideways. I am getting ready to do a intake swap myself, and was curious about your comments about the intake being a POS. Was this a OEM intake? What about it was bad?

It was an OEM intake. The PO cracked it when he drilled and "tapped" it for a temp sensor in the rear driver side coolant passage. When my son drained the coolant for the last swap I could hear the air being sucked in at that point.

I did the swap many years ago on my 98 GT. And it went fine. All I had to do was use the RTV in the right spots and it worked fine afterwards.

01yellercobra · Apr 7, 2019

Did Ford not want the engine and transmissions to come apart in the car? We made it to the point of removing the torque converter nuts, but I'll be damned if I can figure out how to do it. When the nut is in the hole it's really close to the center of the block. Makes it hard to get a socket on. And when I do theres no room to swing the ratchet. I tried going through the motor mount but it didn't work out. So tomorrow we're pulling the engine and trans together.

01yellercobra · Apr 7, 2019

For those wondering if it was really that bad.....

01yellercobra · Apr 10, 2019

I should probably change the title of this thread. The replacement engine showed up today. And I refused it due to all the damage from shipping. I was told it was a running engine. Yeah, not so much anymore.