5.7 head gasket repair

[Archer]

My head gasket went out on my work van 5:00 pm Friday the 13th. I got everything buttoned back up but now my temp gauge is maxxing out. I replaced the one on the d-side of the block and the one at the thermostat but it's still maxxing out even before the t-stat is opening. Any ideas? Is it some other sensor that's gone bad or in the Computer? Any help would be appreciated...

[Archer]

Been thinking, could it have air trapped and I'm reading vapor temp? I put the side one in before it had any fluid and it was in a bad spot and I figured it'd be easier while I had it apart. The one by the t-stat was done after initial startup when I seen my temp gauge spike. When I changed it out there was fluid right up to the t-stat but I guess there could still be air trapped somewhere. Do I have to remove the t-stat and the top rad. hose to get the air out, or should it work it's way out itself?

[Matty]

That is what i would think. It would be pretty random for a head gasket and a temp sender to take a dive at the same time.

If it will self bleed depends on the vehicle. As long as the radiator cap/overflow is the highest point in the system, it "should" bleed using the overflow can. Being that it is a van, this might not be the case, some vehicles have bleeder screws on top of the thermostat housing. I have a bleeder set up, it's basically a funnel with a radiator neck adapter on the bottom. Fill it up, and let the vehicle run and it self bleeds.

This is the funnel:
http://compare.ebay.com/like/40008028513...s&var=sbar

[The Boss]

t-stat upside down by chance? it does not always bleed, but with the rad cap off it should. you can try "pumping" the upper hose to get fluid/air to move in the system. i can usually get a few more bubbles out that way.

[Matty]

(01-17-2012 08:52 AM)The Boss Wrote:  t-stat upside down by chance? it does not always bleed, but with the rad cap off it should. you can try "pumping" the upper hose to get fluid/air to move in the system. i can usually get a few more bubbles out that way.

That will sometimes do it. I know I have had a heck of a time bleeding the air out of some vehicles.

[Archer]

I'm seriously thinking it's something electrical. This morning when I went out the temp was still up in the 200's. As soon as I started it it went down to around 120 and climbed right back up to maximum within 2 minutes. I know it can't be heating up that fast.

I still wasn't getting any fluid through the upper hose so I opened the t-stat up (you had me second guessing myself all night boss-thanks-lol) and removed it and put it back together wondering if for some reason I got a bad t-stat (yes I know you can boil them in water to check them). I now get fluid through but it definitely is not as hot as the gauge says. Even after 5 minutes of running I can put my hand and hold the hose or set them on the valve covers. If it was really over 260 I'd burn the crap out of my hand. I'm lost and I have to get this thing back on the job. Frustrating...

BTW: no codes...

[Matty]

It doesn't seem like it should climb that fast even with no water flow at all, unless there is no water in that jacket on the head and you just getting a reading from the manifold, i.e., air in system or a blocked jacket from the new gasket.

Electrical wise, the sender on the driverside is for the gauge an the one up on the intake feeds the computer. Is it possible you replaced the sending unit with a bad one? It just is a pretty steep coincidence that it would go bad at the same time the head gasket took a dump.

[Archer]

(01-17-2012 03:10 PM)Matty Wrote:  It doesn't seem like it should climb that fast even with no water flow at all, unless there is no water in that jacket on the head and you just getting a reading from the manifold, i.e., air in system or a blocked jacket from the new gasket.

Electrical wise, the sender on the driverside is for the gauge an the one up on the intake feeds the computer. Is it possible you replaced the sending unit with a bad one? It just is a pretty steep coincidence that it would go bad at the same time the head gasket took a dump.

When you say Blocked jacket, do you mean the gasket could have moved and blocked one off or are you thinking something internally?

I'm thinking I still may have some air in there but it doesn't really explain why the temp sender max's out so fast. As far as the sender on the block, I accidently tore the wire when I took the exhaust manifold off thats why I replaced that one. I replaced the on at the t-stat after the gauge started maxxing out.

I took it for a ride this afternoon. Talk about white smoke, wow, I could not see behind me at all. Cars were slowing down to enter the smoke screen...lol It did get better but didn't clear up completely yet. I know when I pulled the #7 plug fluid ran into my exhaust pipe big time. I'm hoping it's just that burning off.

It ran fine, except the gauge is still maxxed out. No codes but I do get a CHECK GAUGES on the dash now. I'm thinking that maybe the gauge went bad when I overheated. I know it's weird but I'm running out of ideas. I'll go to the junkyard this weekend and grab a cluster.

When I got back I let it idle for about a half hour, no overheating. The top hose was hot but the bottom was cool. Even the tranny lines weren't hot. The radiator and cap were both slightly warm. I still think I have some air...

Am I thinking right here?

[Matty]

You got coolant out of the plug before or after the gasket and driving?

White smoke is pretty common after a HG change, I did one on my 4.0 TJ last year and it took a day or two before it was cleared out of the exhaust.

It's not common, but I have seen head gaskets that either were incorrect and blocked a water jacket from the block to the head, of where the port flat wasn't punched out, it's rare, but it happens. Did you check to make sure the head gasket had openings for all the water jackets?

When the gasket went, was it one of those things that just went or were there symptoms leading up to it?

I agree that it is strange to warm up that quick and it makes me think faulty sensor too, but if I remember right, the sensor is between two exhaust ports, so they could heat the area that fast if there is no water present. The sensor is in a water jacket, so if you pull the sensor now, coolant should run out, ruling that out.

How's your heat? If it's good, I think I would rule out blocked water jacket, and go with bad gauge, sending unit or wire. Since the wire was broken and the sending unit replaced, it makes sense.

[ZacD]

Sounds like everything is correct. If you have the inclination to do so, you can probably go buy a cheap temp gauge from the parts store (like a 2-1/16" or 2-5/8" Sun Pro gauge) and plug that thing into the block where the factory temp sender for the dash temp gauge threads into the block and run the thing up to temp to see what it's reading.

You might have some air in the system but I think you're right in there's an electrical gremlin somewhere (either the gauge itself is foul or there's something wonky going on elsewhere).


When you say you ran it down the road and white smoke was apparent, about how long (in minutes) did you drive it? That's a bit leery to me. There might be some coolant being burnt out of the cylinders and exhaust system, but with what you've described having fired the thing up and run it as long as you have, I'd think about all of that stuff would have been burnt out of the system by now. The coolant in the cylinders, for sure, has to be gone. Unless you got that thing sufficiently hot that it cracked the block and is weaping coolant into the cylinders or the head gasket isn't sealing (or the other head gasket is leaking, as well).