Coolant Leak Woes

naturist · **Posted:** Thu May 24, 2012 6:59 pm

Oh, I did the job, just hooking it up the way it was. THAT wasn't the problem. I just wanted to try and figure out what all the hoses were for! And of course, make sure that as unlikely as it was that somebody screwed it up, that I got it right.

It was easy enough to take off, although a bit of a pain in the butt, due to the tight quarters. I had to remove my Provent, too, in order to have room to work, but I got it off, put the new one on, and if it still leaks, I think I know where the problem will be found: the hose that comes off the bottom of the tank, #7 in the drawing-that-is-wrong, doesn't seem to fit all that tightly. If the hose clamp does its job, it'll be fine; but if not, it'll prove the leaker.

I note that the tank is evidently designed in two compartments, such that any coolant escaping the cap is supposed to be caught in the second compartment. There's a small hole at the back to vent THAT to the atmosphere. My second compartment has been full for quite some time, suggesting to me that at least some of my losses were due to the pressure cap.

Anyway, I do still want to see the correct diagram, if anybody has one. My wrong diagram is from the 2005 manual -- maybe the 2006 has the right diagram? Anybody???

bugnout · **Posted:** Thu May 24, 2012 9:22 pm

Just checked the 2006 manual, it has the same picture as the 2005 manual

papaindigo · **Posted:** Fri May 25, 2012 11:39 am

Ok I'm a bit old school so bare with me. What we call the coolant bottle or tank is not exactly that. On many vehicles going back to the late 1960's you had a radiator with a pressure cap and a hose running to a coolant overflow tank such that when the engine got hot the pressure cap would open enough to divert extra presssure and coolant to that tank and as the engine cooled down coolant would be sucked back into the engine until the pressure cap closed. This setup superseded earlier systems that simply vented excess pressure and coolant to the ground which led to constant air in the system and routinely having to top off coolant.

On our system that tank is split into 2 parts. Part 1 under the pressure cap is essentially the top of your radiator. Part 2, on the driver's side is the coolant overflow tank. So you have 4 (not 3) hoses of slightly different diameter. Hose 1 is a small hose running into Part 1 on the top driver's side from the "degass" port on the thermostat which is the vertical small port. This is designed to vent air out of the cooling system into the coolant overflow tank above the level of the coolant. Hose 2 is somewhat larger and runs from just under the pressure cap over to the side of Part 2. This hose provides for coolant flow to and from the overflow tank IF the pressure cap is working properly and there are no coolant system leak problems causing low or high coolant pressure. Hose 3 is the largest hose and runs from the bottom of Part 1 down to a connection on the lower forward passenger side of the engine (I suspect essentially to the water pump or near there). Hose 4 is about the same size as hose 1 and runs from the back passenger side of Part 1 to the driver's side top of the radiator. Don't ask me which direction coolant flows thru hoses 3 and 4 as it could be either direction.

Generally there should be no coolant in Part 2 except when the engine is hot although a tiny bit is not cause for concern.

Hope this makes sense and helps.

naturist · **Posted:** Tue May 29, 2012 7:06 pm

Well, the new reservoir and cap seem to still have a problem.

The cooling system does indeed blow over a slug of coolant into the secondary catch tank when it heats up. But it stays pressurized when it cools and doesn't suck the coolant BACK into the main chamber. I'm going to apply the ole turkey baster to it and manually return the coolant from the secondary tank to the main tank. It appears to my eye that the amount in the secondary tank is just about equal to what I need to return the primary chamber to the full-when-cold mark.

There is no sign of coolant in the oil, nor any oil in the coolant. There also does not appear to be any coolant missing, it just isn't making the trip back to the primary tank when it cools. As though a slug of gas of some sort is making its way into the cooling system.

A blown head gasket and I would suspect the oil/coolant mixing to take place. Especially since it seems to remain pressurized when cold. If there were a leak between coolant and cylinder, such that compression blew a little air into the coolant, I'd expect the coolant to leak back into the cylinder, thence into the oil, or at least disappearing into the exhaust, and I don't see signs of either.

Any suggestions about where to look for a one-way air-in sort of leak?

user113 · **Posted:** Tue May 29, 2012 9:48 pm

you might try flushing out the overflow hose to make sure there is no foreign crap in there acting like a check valve.

grywlfbg · **Posted:** Wed May 30, 2012 1:55 am

naturist wrote:

Well, the new reservoir and cap seem to still have a problem.

The cooling system does indeed blow over a slug of coolant into the secondary catch tank when it heats up. But it stays pressurized when it cools and doesn't suck the coolant BACK into the main chamber. I'm going to apply the ole turkey baster to it and manually return the coolant from the secondary tank to the main tank. It appears to my eye that the amount in the secondary tank is just about equal to what I need to return the primary chamber to the full-when-cold mark.

There is no sign of coolant in the oil, nor any oil in the coolant. There also does not appear to be any coolant missing, it just isn't making the trip back to the primary tank when it cools. As though a slug of gas of some sort is making its way into the cooling system.

A blown head gasket and I would suspect the oil/coolant mixing to take place. Especially since it seems to remain pressurized when cold. If there were a leak between coolant and cylinder, such that compression blew a little air into the coolant, I'd expect the coolant to leak back into the cylinder, thence into the oil, or at least disappearing into the exhaust, and I don't see signs of either.

Any suggestions about where to look for a one-way air-in sort of leak?

Not necessarily. This is exactly what mine was doing w/ a warped head/blown head gasket. I did exactly what you did too. First tried a new cap, then new tank. Then figured out it was over-pressurizing and blowing out the overflow. Over time it would blow more and more coolant out the overflow until my wife would get a low-coolant light after about 25 miles from a full tank.

Dealer tested the coolant and oil and didn't detect coolant in the oil or exhaust gas in the overflow tank. So they initially thought the problem was the t-stat. Only after that was eliminated and reading about racer's trouble (follow the link in my post up-thread) did we pull the head and measure it.

Basically there is a ton of pressure from the exhaust side pushing past the head gasket but there's fairly little pushing the other way so the head gasket can keep the water out, it just can't keep the exhaust gas in.

naturist · **Posted:** Wed May 30, 2012 8:21 am

Thank you, @grywlfbg for the account of your experiences. Blown head gasket (with or without warped head) is my big fear, and may indeed be my problem. I've had overheating problems with this vehicle while towing, but not since last August. The cool weather, limited towing, and replacement of the fan clutch with the heavy-duty Hayden unit seem to have fixed that issue. My leak just started a couple weeks ago.

The leak is as yet smallish, taking maybe 400 miles to move enough coolant to the overflow tank to cause a low coolant light, so it appears I can get by for now with the turkey baster thing. I'm about to head out on a 6,000 mile trip towing again, so we'll see how that goes.

I like this little tractor, but it has been the most troubled vehicle I've ever owned, and I got my first car in 1967. If it has a blown head gasket, and especially if the head is warped, I will be finding a new tow vehicle.

racertracer · **Posted:** Wed May 30, 2012 8:56 am

Naturist, From what your are describing, I can see that you will have a larger leak sooner than you think. Your leak will get worse and I wouldn't trust it to go 6000 miles. Plan on taking at least 30 gallons or more of water with you to replenish the system as you go. If the coolant evaporates too much, it will cause even more damage by warping the head and you will never know that the coolant is low as you drive because the temperature guage will not warn you in advance, due to vapor or an air pocket in the system.

naturist · **Posted:** Thu May 31, 2012 7:26 pm

Latest news on my issue: took a close look at the coolant reservoir, and the hose coming from the top of the radiator to the side of the reservoir shows a substantial stream of gas bubbles coming at idle. Step on the throttle just a wee bit to rev it up to 1500 rpm, and that stream of bubbles becomes very substantial.

Took it over to a BMW/Mercedes shop (not dealer, but owner is a BMW and diesel certified wrench), and he tested the gas coming out of the reservoir with the cap off. It tests positive for exhaust gases.

Yesterday on his recommendation I tried putting a can of Bars Leak cylinderhead formula in it, hoping for the best. It has been through a number of heating/cooling cycles, and the gas flow is getting worse, not better. When you shut it off after driving it, there is a pronounced gurgle for about a minute, very noticeable in the silence. Actual loss of coolant, however, appears to be minimal if at all.

So looks like it is the head gasket. The trip towing the trailer has been cancelled, there's no way this baby is going to go another 6,000 miles. We'll take it in for surgery instead. (sigh) It's only money, eh?

racertracer · **Posted:** Fri Jun 01, 2012 1:16 pm

Get SirSam to do the work.... he travels about the country repairing CRDs at a very reasonable price.

naturist · **Posted:** Fri Jun 01, 2012 3:29 pm

racertracer wrote:

Get SirSam to do the work.... he travels about the country repairing CRDs at a very reasonable price.

Might be so, but sez here he's in Colorado, about 2,000 miles away from me. My planned-and-now-scuttled trip would have put me in his vicinity, or at least passing by, but The Universe intervened.

But thanks for the suggestion.

racertracer · **Posted:** Sat Jun 02, 2012 12:46 pm

Where are you located?

LMWatBullRun · **Posted:** Mon Jun 04, 2012 9:32 am

Me, I would invest in a set of ARP studs at the same time as the HG.
You'll want a m12x1.75 tap, too, (extension taps are about $75 from MSC,) to clean the holes; there is a steel HG available, too.

This sort of failure, RT, is indicative of exactly the sort of random stochastic event to which I was referring; owner does everything right yet gets an inexplicable HG failure. It is true that this is a small percentage of the CRDs out there, but to the person who has to deal with it, even once is too many. When you are riding on the edge of what conventional TTY head bolts in an AL head/CI block will do, then all it takes is some tolerance stacking to accumulate and one of the TTY bolts isn't clamping as it should. (hole just a little tight, bolt just a little big, head just a little soft/rough.....) Then, eventually, you get HG failure.

Stuff like this is why the TDI community and the D24 community has gone to studs.

naturist · **Posted:** Wed Jun 06, 2012 2:47 pm

The verdict is in: the head is cracked.

Oh, happy, happy, joy, joy. (Note the dull monotone in my typing.) Now to start buying the assorted parts required. Anybody got any recommendations of suppliers with fair prices? Places to avoid like the plague???

naturist · **Posted:** Thu Jun 07, 2012 4:38 pm

Well, we're replacing the timing belt, tensioner & idler, water pump, and serpentine belt while we've got it apart, and the total for parts looks like about $2100 including shipping. (core charge is $300, shipping is $271, pretty much a wash there.) Won't know final on labor until the job is done. But, gee, I'll have an almost-new engine (he says brightly). It will be interesting to see if the Hayden fan clutch, which engages at 170˚F instead of the stock 190˚F will carry the engine beyond the NEXT 150,000 miles.

If anybody would like part numbers . . . .

racertracer · **Posted:** Thu Jun 07, 2012 5:23 pm

Don't forget to replace your radiator and flush out the heater core..... A must.

grywlfbg · **Posted:** Thu Jun 07, 2012 7:10 pm

Ugh, sorry to hear that. This seems to becoming a common failure mode... :cry:

I ordered all my stuff from MPA and they were easy to deal with and prices were good. Shipping to NorCal from Oregon wasn't bad.

But like you said, you'll have a mostly new engine so she'll be gtg for awhile.

I'm curious about the fan clutch - isn't everyone clamoring to have 192F thermostats installed and if so wouldn't that mean the fan will run non-stop?

CATCRD · **Posted:** Thu Jun 07, 2012 7:24 pm

grywlfbg wrote:

I'm curious about the fan clutch - isn't everyone clamoring to have 192F thermostats installed and if so wouldn't that mean the fan will run non-stop?

The water inside the radiator might be 192, but the air coming off the rad isn't that high. The air warms up a little, the water cools off a little, and they approach a temperature somewhere between ambient and the water temp.

naturist · **Posted:** Thu Jun 07, 2012 9:49 pm

Yeah, what he said.

The stock fan clutch (when it is working, which evidently is only for the first 10 or 20 thousand miles, piece of junk that it is), is supposed to kick in at 190˚F, by which time the coolant temperature is somewhere above that. In my experience, when new, about 230˚F, later, much higher.

That appears to be too late. The 170˚F clutch should kick in when the coolant is more like 210˚F, when you still have a chance to cool things off without cracking the head or blowing the head gasket.

In my overheating episodes, ambient was always above 90˚F, I was towing and climbing a hill. And when, at long last, the fan DID kick in, it cooled things off just fine. The problem was the darn thing wouldn't kick in until the computer was well into reduced fueling to try to prevent damage. Which, evidently, it was unsuccessful in doing.

So, @racertracer, of course I plan to do a flush on the cooling system. But why replace the radiator? It seems to be fine.

ChooChooman74 · **Posted:** Thu Jun 07, 2012 10:57 pm

Looking at this thread, my next mod is probably a fixed fan.

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Coolant Leak Woes

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