Engine overheating... - Lateral-g Forums

rockdogz · #1 08-23-2008, 10:36 PM

Help, my motor is stumbling....

Ok, so I've never had any engine problems up to now, and the other night the family and I go on a cruise. We're coming home and all of the sudden I lose power. I'm able to make it to a parking lot and we notice that I have some coolant on the ground - maybe a quart. I'm thinking there was a leak somewhere, but I don't find one. It's dark so I call for a flatbed, but seem to be able to drive it around the parking lot ok.

I thought it may be a bad thermostat, but I tested it and it opens at about 180-185 or so. However, the coolant temp is getting up way over 200 which is unusual. Maybe a water pump issue? Strange on an engine with fewer than 2000 miles.

I have the Diacom RamJet diagnostic software, and ran the engine for a while and gathered some data. It was just idling, but I tried to rev it up a little to get the temp up there. The twin Spals spun up and were working.

Here is the number of minutes the engine has run, and the coolant temperature:

0 107
1 108
2 126
3 145
4 153
5 206
6 212
7 212
8 212
9 216
10 218
11 218
12 221
13 226
14 229
15 234
16 238
17 239 (engine off)
18 231
19 221
20 210

The gauge inside showed even higher temps, approaching 250.

Most importantly, I'm wondering if these high temps would cause the engine stumble and lack of power due to the fuel injection system. If not, any ideas there? Things like a clogged fuel filter don't seem to be an explanation since it will run fine for a couple minutes until it heats up.

I'm also trying to figure out what the cause of the high temps could be... water pump maybe? I'm running the reverse flow Vintage Air Front Runner water pump.

Thanks for any ideas!!

67ragtp · #2 08-24-2008, 07:15 AM

Tom,

sorry to hear the problems, fuel pressure / A/F ratio / and Timing may be a good start. If you can put a light on it and it matches the diagnostics software your in good shape there. Fuel pressure at the rails, are headers glowing? Of course water pump failure a possibility. Upper hose getting hot? pull some plugs have a look, dump oil and inspect.

Rich

awr68 · #3 08-24-2008, 10:12 AM

Tom that doesn't sound good or fun....hopefully it's an easy fix like water pump...especially since your are trying to sell the car. Perhaps this is a sign that you need to keep it?

Do you want this moved to the engine forum...might get more exposure there.....

**camcojb** · #4 08-24-2008, 11:01 AM

if it's heating up at idle I look at airflow through the radiator first. I've had twin Spals that wouldn't keep an engine as cool as I wanted, but they didn't go that high. Make sure they have 13+ volts when running; an old stock wiring harness won't usually have full voltage up to the front of the car, and your voltage could be quite a bit lower than you think. Lower the voltage, slower the fans spin.

Also, how did you fill the system with water. An air pocket will also cause this and if you filled through the radiator and don't have a drilled thermostat that's another thought for your problem. Often there will be an air pocket up high at the thermostat area and it'll never open. I like to use a drilled thermostat (or drill 3-4 1/8" holes myself around the perimeter) to allow the water to bypass and push the air out. I also fill the block first through the thermostat area (remove it, fill until the block is full, re-install thermostat and upper hose) and then finish filling the radiator itself.

Very retarded timing will also cause them to heat up, but I assume that's been checked and is in the ballpark; if not, check it.

Jody

rockdogz · #5 08-24-2008, 02:29 PM

Thanks for the ideas...
I have a new wiring harness and don't think voltage to the fans is an issue, but I will make sure.
I did drill the thermostat - the FrontRunner instructions told me to do that. Would that ensure that no air pockets exist, or would you recommend still filling the block first? I agree that an air pocket sounds like it could be the culprit, I'm just not sure how it would have gotten in there if it had been fine before and not having filled the radiator recently.

**camcojb** · #6 08-24-2008, 02:57 PM

Quote:

Originally Posted by rockdogz

Thanks for the ideas...
I have a new wiring harness and don't think voltage to the fans is an issue, but I will make sure.
I did drill the thermostat - the FrontRunner instructions told me to do that. Would that ensure that no air pockets exist, or would you recommend still filling the block first? I agree that an air pocket sounds like it could be the culprit, I'm just not sure how it would have gotten in there if it had been fine before and not having filled the radiator recently.

probably not an air pocket if you drilled the thermostat. Has it always had a heating issue, and is it only at idle? What size are the fans?

rockdogz · #7 08-24-2008, 04:27 PM

No it has not had any cooling issues until now - usually not over 180. It may get hotter while idling on a hot day, but I would say not over 200 and it comes back down when I get moving again. There are two 12" fans.

After filling the radiator yesterday, today it is down a couple inches when I checked... I will drain it and check the fluid before filling it back up and checking the timing. I pulled the plugs and didn't see any apparent issues.

rockdogz · #8 08-24-2008, 06:25 PM

Ok, drained the fluid and it looked fine. Re-checked timing at 10 degrees BTDC. Engine still got way hot. One thing that I'm noticing - the lower radiator hose is not collapsing, but it is also cool enough to touch while the coolant temp is over 200. Is this normal? Could the water pump not be working? Not sure how to check that besides maybe pulling the lower radiator hose and trying to see the impeller turning.

**camcojb** · #9 08-24-2008, 06:38 PM

that will be the coolest water in the system as the radiator has done it's job and that's where the pump pulls the water into the engine. Should still be pretty warm, not sure you can hang onto it, I've never tried.

Starting to wonder about the thermostat, or possibly the pump. Leaning towards the thermostat.

Jody

rockdogz · #10 08-24-2008, 06:49 PM

I've already pulled the t-stat and put it in a pot of water on the stove with a meat thermometer, and it opened at 180-185 or so. Wouldn't that rule it out? The system is pressurized as I can not squeeze the bottom hose while it's hot, but it is cool to the touch... I think the t-stat isn't opening or the pump isn't circulating the coolant. I guess even though I tested the t-stat, it's easier to replace that than removing the water pump...