Water temp hit 220 today...an tips in diagnosing?

[rjd2]

Hi all, so I had my car out this morning in the hot central Ohio weather(85-90 ish, very humid), and by the time I got home, the gauge just barely passed 220F-probably 225 or 230. I have noticed the car running hotter than usual this summer. I replaced my alternator/belt this year, and experienced a bit of belt slip above 4k RPM for a bit. Tightened the belt, and it has gone away. I have been pushing close to 220F for the last 2 months or so. It has been unseasonably hot and humid here. I have a new radiator in the car, fans are kicking on around 180 or so-they appear to function properly. I did a fuel delivery rebuild and o-ring replacement at the intake manifold, but did not do the water pump/thermostat. Here are WP images; I have never seen any leaks at the seal. What are your guesses as to cause, as well as suggestions for possible fixes? I have taken the WP housing off of another D, but it was done when the intake manifold was already off. Can I replace the WP and thermostat without removing the top end/intake portion of the motor? I'm not trying to be lazy, but if so, that's something I could do in an afternoon, and continue driving the car through the season, rather than wait til the winter and do a bigger teardown. Thanks for any advice!

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[Ethan Rode]

It is not possible to replace the water pump without removing the intake manifold. It shouldn't take more than an hour or so to get the induction manifold and the intake manifold off.

I find the most common cause of any overheating issues is a small leak in the cooling system. A cooling system pressure tester is a good start, but the leaks don't always reveal themselves when the coolant plumbing is cold. It only takes a tiny leak to cause overheating.

Perhaps you could put the car up on jackstands, and inspect with the car hot before you go taking things apart

[rjd2]

Thanks. I should be able to get the car up and check for leaks. So I understand, is the most common situation with small leaks caused by them running the sytem dry, or losing pressure? I can guarantee I have not seen any coolant on the garage floor since I have owned the car.

[Rich]

I have been pushing close to 220F for the last 2 months or so. It has been unseasonably hot and humid here. I have a new radiator in the car, fans are kicking on around 180 or so-they appear to function properly. I did a fuel delivery rebuild and o-ring replacement at the intake manifold, but did not do the water pump/thermostat. Here are WP images; I have never seen any leaks at the seal. What are your guesses as to cause, as well as suggestions for possible fixes?

Start with the usual suspects.

Since your rad fans are cycling ib it means the thermostat is opening, at least partially.

Air in the radiator is a common issue with "runs hot" issues.

You replaced the radiator. Are you sure the rad is completely bled? There's a 5 minute check/fix method. With just a screwdriver and no jacking.

[David T]

Here are some checks to make sure the cooling system is functioning as it should;
Make sure the header tank is 1/2 full when cold and you have 50/50 soft water and anti-freeze inside and it is not over 5 years old
Make sure both fans are running and the fan blades are not spinning on the motor shaft
Make sure there is nothing blocking the air inlet grill
Make sure the circuit breaker for the fans is NOT cycling. It has to be the uprated one so it doesn't keep popping. Only the "O" switch should cycle the fans when the A/C is not running.
The temperature gauge is not all that accurate but if you notice it is hotter than usual it is a good sign something is not right.

[rjd2]

thanks for the tips folks! I'll go through these. at some point, I do need to replace some of the short 2" rubber coolant hose lengths; we did the larger rear hoses when installing the new radiator, but the harder to access ones were skipped. they hold now but eventually I'll need to do them, at which point i may just replace the thermostat and WP.

can you detail the 5 minute check for air in the radiator, Rich? thanks!

[Rich]

....can you detail the 5 minute check for air in the radiator, Rich? thanks!

Sure. This radiator air-bleed method works because the expansion tank is about 15 inches above the top of the radiator. Venting the radiator at the top lets tank coolant fill it to the top.

The rest of the system needs to be bled, too, though. This only bleeds air from the radiator and the hoses at that end.
(The process is for an OE system without an aftermarket bleed valve at the top of the small hose at the radiator)

PREP
- Keep the car level. Crank the steering left so it easy to access the right side of the radiator. Prep the area - you will lose some coolant up front.
- Start with the overflow tank at least half full. Leave the cap off.

VENT-BLEED
- Loosen/remove the small hose from the upper right nipple on the radiator. Block the flow with your thumb when coolant flows from the hose.
- At the same time keep an eye on the exposed upper nipple. If nothing comes out right away then the rad had some air in it.
- If you see coolant flow out of the nipple as soon as you pull the hose off just shove the hose back on. The radiator was already full/bled.
- Otherwise, when you see coolant flowing from the upper nipple replace the hose and tighten its clamp.*

INSPECT and CLOSE
- Refill the overflow tank half full if needed. Replace the cap.
- Clean up the mess. You're done.

* If the radiator nipple doesn't start flowing coolant eventually then the overflow tank and the big hose beneath it probably ran empty. Reattach the small hose to the rad, refill the tank, then repeat the air bleed step.

[rjd2]

Thanks! I'm on it. I actually ordered a valved bleeder kit for that exact hose at the rad, so I may just shotgun all the old 4" length main rad hoses, refill, and rebleed. Considering doing the thermostat while I do it, since it's easier to access. (minor aside; I realize I had my AC on 2 or 3 when my temp tipped over 220, so that may be a factor there? Either way, in the next year I think there's some preventative maintenance to be done).

Sure. This radiator air-bleed method works because the expansion tank is about 15 inches above the top of the radiator. Venting the radiator at the top lets tank coolant fill it to the top.

The rest of the system needs to be bled, too, though. This only bleeds air from the radiator and the hoses at that end.
(The process is for an OE system without an aftermarket bleed valve at the top of the small hose at the radiator)

PREP
- Keep the car level. Crank the steering left so it easy to access the right side of the radiator. Prep the area - you will lose some coolant up front.
- Start with the overflow tank at least half full. Leave the cap off.

VENT-BLEED
- Loosen/remove the small hose from the upper right nipple on the radiator. Block the flow with your thumb when coolant flows from the hose.
- At the same time keep an eye on the exposed upper nipple. If nothing comes out right away then the rad had some air in it.
- If you see coolant flow out of the nipple as soon as you pull the hose off just shove the hose back on. The radiator was already full/bled.
- Otherwise, when you see coolant flowing from the upper nipple replace the hose and tighten its clamp.*

INSPECT and CLOSE
- Refill the overflow tank half full if needed. Replace the cap.
- Clean up the mess. You're done.

* If the radiator nipple doesn't start flowing coolant eventually then the overflow tank and the big hose beneath it probably ran empty. Reattach the small hose to the rad, refill the tank, then repeat the air bleed step.

[Rich]

Thanks! I'm on it. I actually ordered a valved bleeder kit for that exact hose at the rad, so I may just shotgun all the old 4" length main rad hoses, refill, and rebleed. Considering doing the thermostat while I do it, since it's easier to access. (minor aside; I realize I had my AC on 2 or 3 when my temp tipped over 220, so that may be a factor there? Either way, in the next year I think there's some preventative maintenance to be done).

Good plan. Two comments on hoses & bleeder kit for best results.

1. Replacing the short coolant hoses under the car: Don't score the aluminum pipes with a razor knife if you need to split/cut the hoses loose. That creates a potential coolant leak. Also look for pitting near the pipe ends when the hoses are off. That can also create a leak depending on where the new hose clamps sit and how bad the pitting is. A coolant pressure tester is important for that job. Or at least a few test drives followed by close inspection of all new connections.

2. Bleeder installation: Depending on its height/placement there may be air trapped in the radiator above it after bleeding. In addition to placing the bleeder close to the nipple you can twist the hose during installation so the bleeder sits higher, near the level of the nipple. Maybe the kit instructions cover this.

You're right, running the A/C reduces the cooling capacity of the radiator since it then gets hotter air coming at it through the A/C condenser.

Final note: If you do a manual bleed at the rad nipple before you drain and perform the upgrades you can discover whether there's air in the radiator - in case you're curious about that issue. For now that's only a suspicion.

[Midnight Specialist]

Build up of corrosion at the base of the cylinder liners?