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Engine Specific Info and Questions => IDI Engine => Topic started by: phaetonv10 on September 30, 2013, 01:54:58 am
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Hey guys.
My mk2 gtd is running great.
But there is something wrong in the cooling system. The fan comes on at the right time and it doesn't overheat. The problem is that as soon as it reaches normal temp, the coolant warning light starts flashing.
If I undo the expansion tank cap when the car is running and at normal temp, water starts to bubble out. Should it be doing that??
I was suspecting a blown head gasket, but I don't see any symptoms of a blown hg like oil mixing with coolant, or water traces in the oil.
Though my coolant is full of rust. I would also like suggestions on how to rid of that.
Cheers
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I presume the coolant is proper mix with water. 50/50 is typical.
The fan indicates that coolant is flowing properly through the radiator. But, are the radiator fins clean, so air can pass through?
I had a failing HG with similar symptoms. It was hard to tell, even with a test for combustion gasses in the expansion tank. Replacing the HG solved the problem.
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If the engine is hot it is normal for the expansion tank to overflow if you open it.
I would assume the light is blinking because your coolant level sensor is confused by the rust in the coolant. Flush the system and refill with proper coolant mix and your issue will likely be solved. FWIW, coolant should be changed every 2-3 years. If it is actually causing rust in your system then all the buffers in the coolant have been gone for a long time and all the parts of your engine touching the coolant are being dissolved and being reconstituted in your radiator. It's very expensive to not change your coolant regularly.
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Just flushed the whole system. Took a small test drive and the warning light didn't flash.
Tomorrow's morning commute would be the more rigorous test.
I ve ordered head gasket anyways. The aaz metal hg.
And I think it ll be a good chance to replace the standard head bolts with arp head studs.
I ve had these head studs lying around for years now.
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Though my coolant is full of rust. I would also like suggestions on how to rid of that.
The ONLY time you get rust in a cooling system is when you get acid in the coolant. That only happens when combustion products enter the cooling system. This means leaking head gasket. You can tell how much acid is in the cooling system by checking coolant voltage. With a DVM set on the Mv scale (.001 vdc) take a reading between the coolant and something brass in the cooling system, like the radiator (if its brass) or a coolant temp sensor. It should read well below .200 volts. If its above .400 Vdc you have problems with the acid and it s eating aluminum parts of your engine. And you have a bad head gasket. This test is definitive.
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Toby that is not true and bad advice to boot. You get rust any time the chemical buffers in the coolant are used up. While combustion gases will cause that to happen faster than normal, it will still happen as coolant gets old. The head gasket is also not the only way for combustion gases to enter the coolant.
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Toby that is not true and bad advice to boot. You get rust any time the chemical buffers in the coolant are used up. While combustion gases will cause that to happen faster than normal, it will still happen as coolant gets old. The head gasket is also not the only way for combustion gases to enter the coolant.
You are absolutely incorrect on this. RUST = Bad Head Gasket. Disbelieve it at your peril. Pure water in a cast iron motor won't get rusty to any appreciable degree w/o acid in the cooling system. Acid caused by the reaction of combustion gasses with water. In 45 years I have never seen rusty coolant that was not acidic. It is easy enough to find out. Just check the coolant voltage.
BTW please name another way that combustion products enter the cooling system, (except for a crack, of course, which is almost always caused by overheating brought on by a bad head gasket)
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Errrm... acids don't attack aluminum, alkalines do...
"Simply stated, pH is the measure of the degree of acidity or alkalinity in a coolant. The acidity decreases and the alkalinity increases as the pH goes from 0 to 14. The recommended pH range for coolants is on the slight alkaline side, from 7.5 to 11. Anything at 11 and above would be considered too high. Tests that range from 6.0 up to 7.5 would be considered too low. The pH of fresh coolant slowly decreases with time and use in a cooling system as acids are formed by the oxidation of ethylene or propylene glycol. At low pH ranges, certain metal surfaces are susceptible to acid corrosion, while at high alkaline pH, aluminum surfaces are susceptible to corrosion. Thus, it is important to check the coolant pH periodically to make sure that it is neither too acidic nor too alkaline."
http://www.cooltrak.com/faqs.asp
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Toby I have personally seen rusty coolant in a vehicle that did not have any head gasket issues whatsoever.
Cracks in the head or block can cause combustion gases to enter and again, I have personally seen them occur without overheating or head gasket issues.
My best guess as to why you haven't seen those things is perhaps in your 45 years you have only seen what you decided to see, and backed it up in your own mind with incorrect information that you believed to be true. 45 years of believing something that is wrong doesn't make it right.
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Just flushed the whole system. Took a small test drive and the warning light didn't flash.
Tomorrow's morning commute would be the more rigorous test.
I ve ordered head gasket anyways. The aaz metal hg.
And I think it ll be a good chance to replace the standard head bolts with arp head studs.
I ve had these head studs lying around for years now.
So, how did your morning commute go?
Also, is the HG you ordered the same as the one you have? As this sounds like it may be your daily driver, I can understand why you would want one on hand as they are not that easy to obtain (especially the one notch). There are three different thicknesses and the best way to find out what you need is to measure piston protrusion. Here's a quick link to the info from the FAQ http://www.vwdiesel.net/forum/index.php?topic=6741.0 (http://www.vwdiesel.net/forum/index.php?topic=6741.0) Having the wrong thickness can either damage the engine (too thin) or make it tough to start (too thick).
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oooor the sensor is fubared
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It went ok. But the hg is on its way out. My conclusion is based on the fact that the rubber coolant pipes get hard as wood. So I think the combustion pressure is leaking into the coolant jacket.
And the rust is back. I flushed the system 3 times before I refilled it. And 2 days later, the rust is back.
Hopefully the new hg, arp studs will solve the problem.
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Agreed, sounds like your on the right track.
Keep us posted.
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The hoses do normally get hard. Normal coolant pressure is 14-15 psi. An easy test for combustion gases is to let the car sit overnight, open the expansion tank cap to normalize the pressure, replace the cap, run the engine for 30 seconds and then loosen the cap while listening for the sound of pressure escaping. If there it is pressurized, combustion gases are likely. Any flaps will also have a kit for testing for combustion gases in the coolant.
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Hey guys.
It's finally done. MLS HG, ARP studs.
It wasn't all smooth sailing though. When I removed the head, it was in bad shape. The water ports around cylinder 3 were all rotten. But luckily I had a spare head lying around which was in great shape. Put that on. And it's been smooth sailing since yesterday. :)
Put in a new speedo cable too, speedo still doesn't work. I don't think the speedo is bad though.
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And the new HG leaks. :(
Oil seeps from the back of the engine, both sides. Got the studs retorqued today to 90 lb-ft. Didn't really work.
I was thinking I will continue driving as is and put some silicone or epoxy glue on the outside to stop the oil from seeping out.
Is it a good plan??
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Neither silicon nor epoxy applied to the outside will do anything useful unfortunately. Once the oil has gotten out of its passage and in between the gasket and the head it will go wherever it needs to till it finds a way out.
What did you do to prepare your head/block for the MLS gasket? MLS gaskets require ABSOLUTELY smooth surfaces or they'll leak. They are nowhere near as forgiving as the composite gaskets.
Also I thought the torque spec for the ARP diesel studs was higher than 90 ft-lbs?
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I did some work in May 2013 on a very low mileage rebuilt 1.9NA engine that had blown a thermostat housing and slightly overheated. I say slightly,
because the overflow tank was pressurizing just a very small amount and coolant had no oil in it & engine oil had no coolant in it. I replaced headbolts
one-by-one with ARP headstuds torqued to 120 ft-pounds - - no change in pressure leak. Then I removed head, checked for warpage (none), cleaned
block deck and cylinder head surfaces throughly, installed new Victor Reinz MLS gasket liberally sprayed on both sides with Hylomar. Torqued same studs
to 120ft-pounds and no coolant pressurization leaks over past 5,000 miles. YMMV
FYI>> my 12mm ARP headstuds instructions called for 120 ft.-pounds of torque. Good luck on your fix.
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I ve driven the car 100 miles since the retorque and it has somewhat worked. I haven't really seen oil under the car.
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And I installed a rebuilt practically unused head. My old head had corroded water ports. So that didn't require much prep, the block was thoroughly cleaned. That's about it. :)
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i believe most users go upwards to 120 ft lbs on these studs...
also, its a really good idea to spray your gasket with hylomar on both sides, unless you know your head and block are PERFECTLY FLAT..
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What's hylomar??
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It is a sealing compound for gaskets, used in aviation and on some British engines.
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The MLS head gasket likes an extra smooth finish, 20RA(machinists roughness measurement), and should not require any extra sealant. Most even specify 'install dry'.
Taken form Federal Mogal tech sheet.
MLS Gaskets - Surface finish
Max roughness <12.5 UM over .8mm sample length.
Max wavyness <10 UM '' 2.5mm '' ''
Flatness <25 UM '' 150mm ''