Overheating v8... Kinda, Slowly climbs on the freeway... 220... Options

[Andyrew]

So driving home from the autox It was very odd...

Driving TO the autox it was 185 the whole way goin 65 (shut up... 2900 for 20 min is not something I liked)

Driving home it was a different story... First bout 5 mins it was about 190. next 2 mins it climed to 195, next 2 mins it climed to 200.
I wasnt really worried. I have in my head that over 220 is bad.
So I played around with speed, my fan and such to see if I could make it go down. but it kept going up. all the way to about 215 when I said that its time for a little rest and pulled off the freeway about 5 miles from home (didnt know at the time) and called dad and some other people to pass the time, ate some beef jerky, bla bla bla...
So right after I pulled off I got out and checked my manual thermostats on the radiator (cooking temp guages stuck all the way in the little holes in the radiator... One on the hottest (top left) and one on the coldest (bottom right) portion of the radiator..
Reading read, 215 hot, 165ish cold....

So after letting it cool for about 10 mins, checking the overflow tank (had about 2 in of coolant in it) and other stuff, I set out again.

Temp jumped right up to 190, then 200 and stayed right there for a little, then bumped to about 205 and 210 some time later. Stop lights are not much of a problem, It stayed at whatever it was at and it generally goes down a tid bit.

Arived home at 215.

Whatcha guys think? Im driving around town now at 200 and 210 ocasionally.

I want it to stay at 190...

IM thinking that I will get my oil cooler installed, Fiberglass the bumper to force air into the front trunk (it can go elsewere currently.. the opening is not sealed by the bumper) and get different fans and shrowd the air. Possibly take off all my copper stuff and check for crimps of any kind.

Andrew

[dlee1967]

Sounds like an airflow issue to me. As I recall, you are venting through the hood and not through the inner fenders. Is the exit hole 2x the air inlet? As RH says, the air expands when it is heated and needs more room to escape.

I found a great difference on my first V8 car when I went from a "special edition" spoiler with a small cutout to a "ultimate" air dam with a large scoop. If made a big difference on the interstate. I also found that there was some room for the air to pass around the radiator on my first conversion (RX7/914). I installed some closed cell foam (not the sh*t in the can from Home Depot!) around the sides of the radiator and this also helped. Forced air follows the path of least resitance and if you have gaps around your radiator, they will allow the air around the unit.

What thermostat do you have? A few folks try to run with no thermostat or just a restrictor. At high rpm, the coolant can be running through the system too fast to properly cool. I use a 160 degree with three 1/8 holes in it to release air and provide a little presure release should the wife try to haul ass down the road before the thermostat opens. This can cause the impeller blades to bend on the Chyrsler water pump.

Finally, the fans should make no difference at highway speeds. The air flow should be enough on its own to cool your car. David Lee

[datapace]

I had similar issues and that's why I got the renegade kit. I'd have issues if I was creeping in traffic, moving it would stay cool for the most part.

(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif) Shrouding may help. Though toasting an engine or warping heads due to overheating is an expensive way to experiement.

I'd be curious to know what the temp was at the *engine* when it was 215 at the radiator with your thermometer. Keep in mind that the coolant is not circulating where you're measuring it. In my experience, I would see temps shoot up even higher once the engine was turned off due to heat soak.

-bryan

[JB 914]

Hi Andrew,

Make sure your air flow is gettng to the radiator as mentioned by the others first. if you are still having the problem then it is air in the system. ask me how i know (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)

[Dad Roberts]

I had dealt with these issues back after I first did my setup in Texas. Most what everyone is saying is correct. Since your previous trip(s?) had been uneventful it appears to be a blockage problem as was mine. Definately not the fans. As mentioned they SHOULD not be needed at freeway speeds. Airflow could probably be improved upon but since it was ok b4, not necessarily the problem. How old is your radiator? Have you done any work on the cooling system lately? I'm a lil bit embarrased to say.... (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif) my blockage was due to overzealous application of silicone......SEVERAL times. Each time I worked on the system.....more silicone. I finally had it blocked so bad it wouldn't cool at all. Unlike most of your setups, mine uses 2" tubing to route the water back and forth. According to experts.....mine shouldn't cool at all (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) ..................Dad (IMG:http://www.914world.com/bbs2/html/emoticons/driving.gif)

[Andyrew]

I hadnt had any problems before because I havent driven it this far before! This was a test...

Radiator is new. Griffin aluminum radiator.

I Might have some "blockage" as far as lines go... I was removing the sodder from some of my copper lines and they warped it a tid bit, caused the end to kind of crimp in a tad. That might be the problem, but I dont know.. Have to fix it somehow by expanding it to round.

I can give it a little more air flow going in at higher speeds by forcing the air in more through ducting. I'll do that....

I DO have 2x air outlet with the hole in the hood. I calculated it out... I'll cut the fender wells out a little and see if that fixes the problem.


I dont think that I will toast a new engine at 220... lol


I did have some air gaps.. one big one under the radiator.. but I put a rubber piece of hose in it to close out the gap... Lemme check to see if its still there... lol... Yup still there... Tie wraps held (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)
Dlee where did you get your foam? I want to try it out a little bit.

Thanks guys. any more ideas would be greatly appreciated!

Andrew

[ewdysar]

So what happened at the AX? The car ran cool before.... (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif) Any possible kinks in your rubber hoses? Did anything shift? Maybe the system needs to be "burped" again. Did you pick up any soft debris on the freeway? Maybe a cone stuffed into your intake. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) Are you getting good flow if you take off the fill cap? (only remove if the engine is stone cold)

This doesn't sound like a slow degrade of the system, more of an event.

Good luck and keep us posted.

Eric

[ewdysar]

More thoughts on this... maybe the waterpump belt is slipping. If the engine was revved hard with the t-stat fully closed (seems unlikely after your drive there) you can damage the impeller.

Eric

[neo914-6]

Bleed and then bleed some more, air pockets are nasty...

[dlee1967]

Andrew, my foam came out of a computer shipping crate. Grey stuff and rather dense. You can get similar material at some fabric stores, but it will be tan. Cut a bit oversized to wedge it in position and then spraybomb it black or grey. If you drive through a load of water, you might pull it to dry out so it doesn't promote rust. I know you said that you put a piece of hose under the radiator, but you should make every attempt to seal all sides (top and bottom) very well. I saw your setup on your build thread but don't recall whether you have a piece of foam sealing the top of the radiator to the hood. Maybe you were using an aluminum shroud? David Lee

[Andyrew]

Lemme put it this way...

I was NOT working the engine hard at the autox...

Just watch my video... listen for the engine to hit the cam... It doesnt happen often.. lol


Nothing happened to the engine at the autox. I was 1/2 throttle at most of the straights and coming out of the corners. I didnt have enough TIME to roll onto the throttle all the way because of gettin up to speed to fast...

Im pretty sure that the T stat was open.. I was in the first run group.

Nothing was amis on the car driving home asside from the water temp SLOWLY getting hotter.

Andrew

[Andyrew]

(IMG:http://www.914world.com/bbs2/uploads/post-2-1095696323.jpg)

I cant really "bleed" just open the cap and add water till its full.

besides it just comes out onto my overflow tank anyways.. I said that I checked the overflow tank and it was 2 in of coolant in it... I had 1/2 in before the trip.

Andrew

[Howard]

Mine comes and goes. Biggest problem is air pockets. But 50/50 coolant water mix boils at around 260 @ 15lbs pressure, so 220 or 230 is no real issue as it leaves the engine.

Where is your temp gauge sender? I have two gauges, one as it leaves the engine (between the exhaust ports) and two as it leaves the radiator. Mine usually runs 220 @ one and 165 @ two. I'm going to add a 2 gallon expansion tank in front of the 'firewall' for a little more reserve.

[Type 4]

When you bleed ths radiator Raise the front of the car up at least a 18 inches off the ground.
This will get all the air out.
Thnis is a trick I learned dealing with Panteras.

[lapuwali]

I just love that all of these water-cooled guys have so many temp sensors. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

I wonder, Andyrew, since you live in the Central Valley (generally a hot place), if air temp isn't causing some of your problems. It was probably cooler in the morning when you went to the AX than it was when you were driving home. Perhaps your system is just marginal enough that you'll have more problems as air temps rise into the rather brutal summertime weather there.

However, since your outlet temp is well below the thermostat temp, it sounds to me like the system is working fine so far. You might want to try to rig up an in-dash temp gauge with the sensor at the rad outlet, as well as the gauge you have now, which I presume is as it's leaving the engine to the rad.

[ewdysar]

Andrew,

I'm just thowing random ideas, so don't take my questions personally.

Is your overflow tank the white tank on your fender? If so, is the hose positioned so that the radiator will pull fluid when it cools off? If the overflow hose can pull air, it will introduce air pockets every time you heat cycle the system.

Sorry, I don't know more about your car, maybe I'll do something else for a while.... (IMG:http://www.914world.com/bbs2/html/emoticons/beer3.gif)

Eric

[914GT]

When your system heats up and the coolant expands and pressurizes, this naturally forces coolant into the overflow tank. After it sits for a few hours and cools, the reverse happens and a slight vacuum occurs to draw coolant back in from the tank. But at this time your radiator hoses are still flexible and if there are any sharp bends that's when a hose might want to kink or partially collapse. So that's what Eric brought up might be a good thing to check, unless the outside air temp went up a lot.

The radiator is really too low to properly keep the whole system free of air. The best place is above the engine which is the highest point in the system. Raising the front of the car is a good idea for the initial air bleed, but over time, there may be air pockets form again which will not get drawn out with the expansion tank at the radiator.

[rick 918-S]

The angle your radiator sits at it appears you have a upper hose that is higher than your side tank. It also appears to be higher than your surge tank.

Your system could be air bound at that hose.

Or your "T" stat could be stuck open allowing the coolant to circulate too fast. What type of radiator do you have?

I use a double pass "Howe" and my surge tanks is mounted higher than my cylinder heads. Like Dad Roberts I also use large tube to transfer the coolant.

You may try the jack up and bleed method suggested in other threads.

BTW: I drove through Chicago stop and go traffic for 3 hours without my fans in 80 degree heat. I think I was at 195 for a while.
I think I actually need a damper on the intake air to bring my engine temp up on the freeway. Runs at like 180.

[dlee1967]

Andrew, now that I see the pictures of your setup, I believe an air pocket is the issue. Measure the height of your thermosat housing to the ground and compare with the top of your radiator. I bet it is about 4" higher. What I would suggest it use a blanking cap on top of the radiator and put a pressure cap in the hose that comes off the thermostat housing. Relocate your (volvo I think) overflow to the engine compartment area. Now you have a cap at the highest point of the system for easy air bleeding. You won't have to jack up the car. Fill the system until the front cap overflows and then cap it and continue to fill at the thermostat cap.

Not really a plug, but David at Desert Hybrids has the in line unit with filler neck or you can buy one from Summit or Jeggs.

David Lee

[andys]

I cannot guess what your specific solution is, however I would consider incorporating a surge tank, which is not the same as an overflow tank. I've used them on race vehicles to great success, an will use one in my V8 conversion as well (good as gold, as far as I'm concerned). The majority of trapped air will accumilate there, and not get recirculared into your system. The referenced link suggests routing a line from the top of the radiator, however there are alternatives that can yeild equally good results.

Read this: http://www.crracing.com/apparel/jackets.html

BTW, I would suggest you should read the other tech stuff on ductwork. The last paragraph is particularly noteworthy.

Andy