Radiator Flushing - Specifics?

Teado · 07-29-2008, 07:25 PM

My 86 MK1 has been overheating quite a bit lately. I have also noticed when ever it over heats, the coolant is consistently quite low. The overflow does have fluid in it, but it doesn't seem to pull fluid back in. I'm thinking that I have some air in the lines that I can't get out and it cavitates around the pump or creates an environment for steam. I also noticed that the resevoir bubbles when the engine overheats, as in steam is being forced out of the coolant loop and into the overflow. I have flushed the radiator twice until clean water came out. Also removed all the small build-up on the outside of the radiator and made sure there was room for plenty of air to travel through the fins. But it's still over heating. Around town it seems fine, but when I go for a trip on the freeway ~ 180 mi. It has overheated every time.

Could this be an air bubble problem? I haven't seen or noticed any leaks, but it seems to go through a lot of coolant / distilled water.

What is the exact/best procedure for ensuring all the air bubbles are out?

tjmr2 · 07-31-2008, 12:00 AM

Overheating can be caused by the timing being too far advanced, check that to make sure it is set as specified, jumpering terminals E1 and T in the service connector.

There are two places you have to bleed air out of the MK1. The BGB recommends placing service hoses on the radiator (Drivers side top) and heater (inside frunk, behind the plastic cover) bleeder valves. Tie up the end of the hoses so antifreeze won't run on the floor, set the heater control valve to hot, open the bleeder valves (cold system) and fill from the water inlet (pressure radiator cap).

The water inlet is higher than the heater and radiator and theoretically all the air will bleed out as you fill the system. I cheated and used a 1 quart bottle and a vacuum bleeder and pulled water and air out of the system at the radiator and heater a quart at a time, making sure the inlet was filled. Since the fluid I was pulling out was clean I just poured it in the filler, adding more each cycle until I didn't get any more air out.

Hope this helps.

tjmr2 · 07-31-2008, 12:12 AM

Oh yeah, if you go through the above and continue to lose coolant you may have a small pin-hole coolant leak in a hose somewhere, if you can't find a wet hose I would recommend a leak down test, you may have a head gasket problem.

Teado · 07-31-2008, 11:42 AM

I'll keep a close eye on it. My father-inlaw has a vacuum bleeder, I might try that approach to make sure all the air is out.

Teado · 08-01-2008, 02:00 PM

Update:

I think I have a pin-hole leak somewhere that doesn't leak till under pressure, hense the loss to fluid only after things heat up....

Now to locate it.

Wish I had a lift about now.

conor · 08-03-2008, 10:04 PM

Have you verified that your radiator cooling fans work? Are you using A/C when the car overheats? Do you have a non-stock front bumper/air dam?

You've seen coolant on the ground after driving your car? Or you just think there's a leak? There are a bunch of rubber hoses that connect the various hard pipes together, so.. I suppose one of them could be having issues after, oh... 20+ years..

Teado · 08-09-2008, 11:49 AM

My cooling fans do work. I tested them already by turning on the A/C which turns on the fans. However with plenty of ram air from higher speeds when the fans won't even be working, the car overheats. I had cruise on at 65mpg on flat ground ~85 deg, and the car over heated... low on coolant. It's got to be going somewhere! How could I test to see if my head gasket is/is not the problem? I am going to trace all the coolant lines this weekend and look for small pin holes. Maybe I'll replace all those crappy factory hose clamps also.

Oh and I haven't seen any coolant on the ground. Only time is if it boils out my overflow, which is fairly rare.

tjmr2 · 08-11-2008, 02:34 PM

Perform a leak down test to determine if you have a head gasket leaking.

Here is a link describing the test:

Building and Using a Cylinder Leakdown Tester

And or Google: cylinder leak down test

That's how I found it and many others. Not hard to build, nor real hard to do, gives great troubleshooting information.

Good luck.

mr2tim · 08-11-2008, 03:53 PM

Maybe our friend from Roseville has a clue. The fans may work, only on a low speed?

When the car is real hot both fans should work, both going full speed.

If your relay at the front trunk is faulty you'll only overheat when on the freeway but not in-town usage?

Does this sound like your symptoms?

Teado · 08-12-2008, 01:43 AM

Quote:

Originally Posted by mr2tim

Maybe our friend from Roseville has a clue. The fans may work, only on a low speed?

When the car is real hot both fans should work, both going full speed.

If your relay at the front trunk is faulty you'll only overheat when on the freeway but not in-town usage?

Does this sound like your symptoms?

Yes and no. I have only been over heating while on the freeway, but once I get off the freeway to stop and let the car cool the system stays hot. And everytime the coolant is low, like a gallon low! So I'm thinking that either I have a good sized leak somewhere that only happens when I'm driving or somehow I'm not getting all the air out of the system and it creates hot spots. I haven't seen any coolant on the ground or anything pooling below the car when it's parked...

Really confusing

A mechanic friend of mine said that my water pump may be leaking, or my temp sensor could be faulty, or I just may have a lot of residual air in the system. I don't think it's excess air that I'm not getting out b/c I've bled a lot of air and put a ton of water in over the last few weeks, it seems to be "using" water as much as gas lately.

Oh and I haven't noticed any white clouds of smoke, but I am going to make a point to pay closer attention to my exhaust.

The car also isn't mis-firing at all, seems to run strong.

mr2tim · 08-24-2008, 03:40 AM

Hmm..if'in I had to confirm a water pump leak I'd pull the middle section and top section of the Timing cover..the pumps have a "weep" hole on the bottom front that should either be wet or actually dripping water (when running). If the inside of the Timing cover looks "greasy" or wet looking the leaks here.

The Temp Sensor for the water gauge on the dash is located at the dipstick location, on the water inlet, it's only 1 wire and easy to troubleshoot.

Look for wet spots on the sides of the rad, or at the bottom on the sides. (copper radiators rot by electrolysis)

Relays?
when ya'll buzzin' the freeway, and the car is hot, a/c off..are both fans on "high" mode (take the black cover off above the rad if needed) if not you -will- boil over. (fans have high and low operation)

Another thought, this may be a pressure only hose leak and you may not be able to view results when the cars cold.

Trust me the water has to go somewhere...you'll find it!

CyFi · 08-24-2008, 03:56 AM

next time you pull over to cool down, check the overflow bottle, if its full up to the brim chances are you have a small head gasket leak and are spitting coolant out of the overflow tank. Go to autozone and get the loan a tool cooling system pressure tester, pressurize your system up to around 17 psi and make sure it holds, also test to make sure your cap is releasing at the right pressure

If the little line going from the filler neck to the overflow tank isnt completely 100% sealed you will suck air back into the system every time the car cools, its like sucking through a straw that has a hole in it.

07-29-2008, 07:25 PM	#1 (permalink)
Teado MK1 = My Daily Addiction Join Date: Jun 2008 Location: Oregon Posts: 272 Thanks: 11 Thanked 9 Times in 8 Posts iTrader Rating: (2/100% )	Radiator Flushing - Specifics? My 86 MK1 has been overheating quite a bit lately. I have also noticed when ever it over heats, the coolant is consistently quite low. The overflow does have fluid in it, but it doesn't seem to pull fluid back in. I'm thinking that I have some air in the lines that I can't get out and it cavitates around the pump or creates an environment for steam. I also noticed that the resevoir bubbles when the engine overheats, as in steam is being forced out of the coolant loop and into the overflow. I have flushed the radiator twice until clean water came out. Also removed all the small build-up on the outside of the radiator and made sure there was room for plenty of air to travel through the fins. But it's still over heating. Around town it seems fine, but when I go for a trip on the freeway ~ 180 mi. It has overheated every time. Could this be an air bubble problem? I haven't seen or noticed any leaks, but it seems to go through a lot of coolant / distilled water. What is the exact/best procedure for ensuring all the air bubbles are out?

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07-31-2008, 12:00 AM	#2 (permalink)
tjmr2 Cage Fighter Join Date: Jan 2008 Location: Colorado Posts: 410 Thanks: 0 Thanked 62 Times in 59 Posts My Google Map iTrader Rating: (0/0% )	Overheating can be caused by the timing being too far advanced, check that to make sure it is set as specified, jumpering terminals E1 and T in the service connector. There are two places you have to bleed air out of the MK1. The BGB recommends placing service hoses on the radiator (Drivers side top) and heater (inside frunk, behind the plastic cover) bleeder valves. Tie up the end of the hoses so antifreeze won't run on the floor, set the heater control valve to hot, open the bleeder valves (cold system) and fill from the water inlet (pressure radiator cap). The water inlet is higher than the heater and radiator and theoretically all the air will bleed out as you fill the system. I cheated and used a 1 quart bottle and a vacuum bleeder and pulled water and air out of the system at the radiator and heater a quart at a time, making sure the inlet was filled. Since the fluid I was pulling out was clean I just poured it in the filler, adding more each cycle until I didn't get any more air out. Hope this helps.

07-31-2008, 12:12 AM	#3 (permalink)
tjmr2 Cage Fighter Join Date: Jan 2008 Location: Colorado Posts: 410 Thanks: 0 Thanked 62 Times in 59 Posts My Google Map iTrader Rating: (0/0% )	Oh yeah, if you go through the above and continue to lose coolant you may have a small pin-hole coolant leak in a hose somewhere, if you can't find a wet hose I would recommend a leak down test, you may have a head gasket problem.

07-31-2008, 11:42 AM	#4 (permalink)
Teado MK1 = My Daily Addiction Join Date: Jun 2008 Location: Oregon Posts: 272 Thanks: 11 Thanked 9 Times in 8 Posts iTrader Rating: (2/100% )	I'll keep a close eye on it. My father-inlaw has a vacuum bleeder, I might try that approach to make sure all the air is out.

08-01-2008, 02:00 PM	#5 (permalink)
Teado MK1 = My Daily Addiction Join Date: Jun 2008 Location: Oregon Posts: 272 Thanks: 11 Thanked 9 Times in 8 Posts iTrader Rating: (2/100% )	Update: I think I have a pin-hole leak somewhere that doesn't leak till under pressure, hense the loss to fluid only after things heat up.... Now to locate it. Wish I had a lift about now.

08-03-2008, 10:04 PM	#6 (permalink)
conor Lord Anti-Rice Join Date: Feb 2005 Location: Roseville, CA Posts: 987 Thanks: 22 Thanked 32 Times in 28 Posts Blog Entries: 1 My Google Map iTrader Rating: (2/100% )	Have you verified that your radiator cooling fans work? Are you using A/C when the car overheats? Do you have a non-stock front bumper/air dam? You've seen coolant on the ground after driving your car? Or you just think there's a leak? There are a bunch of rubber hoses that connect the various hard pipes together, so.. I suppose one of them could be having issues after, oh... 20+ years..

08-09-2008, 11:49 AM	#7 (permalink)
Teado MK1 = My Daily Addiction Join Date: Jun 2008 Location: Oregon Posts: 272 Thanks: 11 Thanked 9 Times in 8 Posts iTrader Rating: (2/100% )	My cooling fans do work. I tested them already by turning on the A/C which turns on the fans. However with plenty of ram air from higher speeds when the fans won't even be working, the car overheats. I had cruise on at 65mpg on flat ground ~85 deg, and the car over heated... low on coolant. It's got to be going somewhere! How could I test to see if my head gasket is/is not the problem? I am going to trace all the coolant lines this weekend and look for small pin holes. Maybe I'll replace all those crappy factory hose clamps also. Oh and I haven't seen any coolant on the ground. Only time is if it boils out my overflow, which is fairly rare.

08-11-2008, 02:34 PM	#8 (permalink)
tjmr2 Cage Fighter Join Date: Jan 2008 Location: Colorado Posts: 410 Thanks: 0 Thanked 62 Times in 59 Posts My Google Map iTrader Rating: (0/0% )	Perform a leak down test to determine if you have a head gasket leaking. Here is a link describing the test: Building and Using a Cylinder Leakdown Tester And or Google: cylinder leak down test That's how I found it and many others. Not hard to build, nor real hard to do, gives great troubleshooting information. Good luck.

08-11-2008, 03:53 PM	#9 (permalink)
mr2tim SUPERcharZed ToyZ RacZer Join Date: Mar 2008 Location: South Florida Posts: 1,789 Thanks: 8 Thanked 118 Times in 111 Posts My Google Map iTrader Rating: (6/100% )	Maybe our friend from Roseville has a clue. The fans may work, only on a low speed? When the car is real hot both fans should work, both going full speed. If your relay at the front trunk is faulty you'll only overheat when on the freeway but not in-town usage? Does this sound like your symptoms?

08-24-2008, 03:40 AM	#11 (permalink)
mr2tim SUPERcharZed ToyZ RacZer Join Date: Mar 2008 Location: South Florida Posts: 1,789 Thanks: 8 Thanked 118 Times in 111 Posts My Google Map iTrader Rating: (6/100% )	Hmm..if'in I had to confirm a water pump leak I'd pull the middle section and top section of the Timing cover..the pumps have a "weep" hole on the bottom front that should either be wet or actually dripping water (when running). If the inside of the Timing cover looks "greasy" or wet looking the leaks here. The Temp Sensor for the water gauge on the dash is located at the dipstick location, on the water inlet, it's only 1 wire and easy to troubleshoot. Look for wet spots on the sides of the rad, or at the bottom on the sides. (copper radiators rot by electrolysis) Relays? when ya'll buzzin' the freeway, and the car is hot, a/c off..are both fans on "high" mode (take the black cover off above the rad if needed) if not you -will- boil over. (fans have high and low operation) Another thought, this may be a pressure only hose leak and you may not be able to view results when the cars cold. Trust me the water has to go somewhere...you'll find it!

08-24-2008, 03:56 AM	#12 (permalink)
CyFi Moved on Join Date: Oct 2005 Location: Phoenix Posts: 1,401 Thanks: 12 Thanked 38 Times in 35 Posts iTrader Rating: (11/100% )	next time you pull over to cool down, check the overflow bottle, if its full up to the brim chances are you have a small head gasket leak and are spitting coolant out of the overflow tank. Go to autozone and get the loan a tool cooling system pressure tester, pressurize your system up to around 17 psi and make sure it holds, also test to make sure your cap is releasing at the right pressure If the little line going from the filler neck to the overflow tank isnt completely 100% sealed you will suck air back into the system every time the car cools, its like sucking through a straw that has a hole in it.