Overheat at speed.

I had given my 2003 Jetta to my son, and he had been taking care of it. I'm trying to reconstruct the events as he's described them, as he has returned the car, with a problem he can't fix.

At 210,000 miles, he had the timing belt done by a local shop: not a TDI-specialist shop (we don't have one here), but AAA-approved. I had used them in the past for work on other cars and generally trusted them.

Car now has 220,000 miles.

At some point after the timing belt job, the lower radiator hose developed a leak. He dealt with lowering coolant levels for a couple of weeks (topping off with either coolant or distilled water) - before he located the problem and replaced the hose.

When he replaced the lower hose, he accidentally broke the plastic fitting on the upper hose, so he had to replace that too. I think it was around this time he noticed "soot in the coolant reservoir". He took the car back to the same shop - and their diagnosis was "soot in the coolant reservoir". No other findings or other action taken.

He brought it back to me, and we flushed the coolant, and replaced it with fresh G12. This was when he started having occasional overheat problems on the highway. We couldn't tell where it was leaking from, but in hindsight, we now know it was leaking from the expansion tank's overflow.

When he could no longer commute to work (10 miles) without an overheat, he left the car with me.

Through each overheat event, he assures me; it never reached the top of the temperature gauge, and it never shut down due to high temperature. I don't think he ever found the expansion tank totally empty either, but I do think the car was probably run with too-diluted coolant for a while.

Here is what I've done:

1. Replaced thermostat (195 F).
2. Flushed and replaced coolant. (G40, which is G12 compatible).
3. Checked water pump: Impeller is fixed on shaft.
4. Checked exhaust gasses in coolant with block tester kit: negative.
5. No coolant in oil.
6. No oil in coolant.
7. Good flow through radiator.
8. Good flow through block.
9. Good flow through egr cooler and heater core.
10. No sign of coolant in exhaust.
11. Engine runs smooth and even, as always.
12. Expansion tank return line shows good flow, no bubbles.

Car warms up at idle to 195 F, thermostat opens. Operating temp stabilizes at 195-196. I can drive around the neighborhood, and temp remains at 192-196. (Temps monitored through ODBC port with an ELM 137 and smartphone with ODBCFusion app).

If I get frisky with it, it goes up to 202-204, and can come back down to 196. When I parked, it went up to 214, and I got out, and checked the expansion tank, again the level was near the top, (instead of halfway between min and max where I had just filled it), and it was visibly bubbling.

I'm kind of at a loss. I don't have a way to do a compression test because my tester does not have an adapter that fits these glow plug holes, and it only goes up to about 300 PSI. Same with the one I could rent at the local auto parts store. I'm not convinced that the head gasket is blown or head is cracked, but I believe I've eliminated all other possibilities.

Head gasket or cracked head. Bubbles in the expansion tank is the tell for one of those.

"He dealt with lowering coolant levels for a couple of weeks" = "Head gasket or cracked head. Bubbles in the expansion tank is the tell for one of those."

.....in all likelihood.

If at all possible, don't go back to the same shop. "He took the car back to the same shop - and their diagnosis was "soot in the coolant reservoir" In my opinion, the shop should have known there was a problem at this point.

Could the EGR cooler be a culprit?

Andrew 179 said:

If at all possible, don't go back to the same shop. "He took the car back to the same shop - and their diagnosis was "soot in the coolant reservoir" In my opinion, the shop should have known there was a problem at this point.

Click to expand...

I'm thinking about seeing if he saved the paperwork and trying to see if there's some kind of warranty I can collect on. I don't know how a timing belt job translates into a blown head gasket; but this has me pretty steamed.

Head gaskets fail on these car, and its failure may be totally unrelated to the timing belt change. It may have started with an overheat because of the broken hose that your son didn't catch. The temperature gauges on these cars provide vague readings at best.

Time to pull the head, get it planed, and put it back together. Your signature says you're running a VNT-17, but doesn't mention a tune. If you're running more than 20 PSI you may want to consider using head studs instead of the OE spec torque to yield bolts.

Okay: I just double-checked everything and re-ran through a warmup.

I *did* forget something. The electric fans.

They DO operate when the AC is on. And I did check that. But I did not check that they come on at Stage I and Stage II. So this morning I did that. They aren't coming on at 195 and 210.

I would get an IR temp gun and shoot the radiator just to make sure those numbers are real life before you start pulling things apart.

h.ubk

Sadly: my IR gun showed the driver's side coolant flange (one with the 3 glow plugs) was 210 after another test drive. I'm not really sure how to hit the radiator - maybe through the front grille? ODBC said 238 F. (I no longer have VDCS - my Windows 7 install perished years ago). I was able to get temp to respond downwards, at-idle when I put the AC on (to activate fans), but not into a reasonable range.

When I idled the car after, with the AC on, the temp stabilized in the 225-ish range, but the coolant in the expansion tank was still nearly full (way past max; didn't see bubbling today) - and I noticed the fans did come down from Stage II to Stage I. So the fans are definitely fine - but maybe the controller or the temp sender are bad, and I'm going to try to walk through the Bentley procedure for that.

But at the end of the day, there's no other explanation for the "Soot event", and also, I don't think I've ever seen the expansion tank fill up like this before. So I think in addition to whatever fan problem I have, I also likely have a head-gasket problem. I'm just in denial.

I don't have the garage space, budget, or time, to do a head gasket on this car. Particularly since we just did the timing belt 10k miles ago.

I think one other possible indicator of a bad head-gasket might be that we also had a recent glow-plug failure.
Wouldn't you know it: I have an endoscope cam, which just BARELY does not fit down these glow plug bore holes!


I AM running a VNT 17, (actually a 15/17?) but no tune. AFAIK, it's stock boost.
Details hazy; but they're probably all on a past posting of mine on this forum - this turbo was supposed to be plug-n-play with the stock turbo, but could be a performance mod with a tune, or more with less restrictive exhaust, injector nozzles, etc. Never went that route. Always intended to someday.

I agree with the head gasket. There isn't enough exhaust pressure in the egr cooler to overcome coolant pressure and make bubbles in your coolant res. If you did the chemical tester for exhaust gases in your coolant I can tell you first hand that its not accurate on diesel vehicles. I've seen lots of diesel head gasket failures that will only leak under load, lots of boost + lots of fuel = high cylinder pressures. Also check to see if you have good heat out of the vents, bad head gaskets put air in the system which makes its way to the heater core.

Symptoms of a failed head gasket:

• Higher coolant temps at highway speeds
• Losing coolant when driving at high speeds
• Hoses are hard when the car sits overnight
• Coolant bottle releases pressure after sitting overnight

If you don't have any of those symptoms and the car is still overheating, it's possible your water pump impeller isn't spinning. This happens sometimes and will cause the car to overheat.

But if you have any combination of the above symptoms, and if you actually do have soot on your finger when you run it around the inside of the coolant bottle, then I think a head gasket replacement is in your future.

FWIW, the ALH engine can operate perfectly normal "without" the coolant system being under pressure. I have a coolant system mechanical pressure gauge on my ALH in the Vanagon. Three years ago while heading out on a very long trip, the tube to the gauge at the dash split causing the system to lose all pressure. I just drove on for 32 days and over 12,000 miles without an overheat, loss of coolant or poor performance.

Although the OP said he checked the water pump impeller. If it has a plastic impeller, it will generally check okay at room temp. Out on the road with full engine temp, those plastic impellers can expand enough to spin on the shaft. I've seen them fail to flow coolant at idle when fully warmed up, especially in gasser engines.

Coolant exits the engine at the end of the head on the transmission side (there at the coolant Glow Plugs). At that point the coolant is at it's highest temperature. So, it is possible to see a little higher than normal temps at that location. The OE temp gauge generally shows 190 at full warm and considerably beyond full warm.

Before removing the head, I'd definitely check the EGR cooler.

+1 for head gasket, happened on mine and a friends but it's not to bad a job. Cured the issue anyway.

No bubbles, just occasional heat but mainly mysterious loss of coolant after harder driving.

Well, I have done this job on two other cars before. This particular car intimidates me because I don't have VCDS, or a way to verify compression after I'm done. I'm hoping I can get the head off and back on with the cam in the exact same position, without having to adjust timing in any way. Does that sound realistic?

I know that since I have a non-stock turbo, I could probably put in a thicker head gasket to accommodate more boost, but then I'd have other issues to deal with that are beyond my level of expertise. Advice?

Say I'm shopping for a "head gasket kit" ... what's the best one out there, and who sells it?

(EDIT: I found the old post - the turbo is a VNT 17, I bought it from tdiclub member dogdots in 2010.)

need4speed said:

I know that since I have a non-stock turbo, I could probably put in a thicker head gasket to accommodate more boost, but then I'd have other issues to deal with that are beyond my level of expertise.

Click to expand...

Don't do this. Although some engine builders will lower the compression ratio and run higher boost, it also causes hard starting and poorer response when off boost. You're better off keeping the CR at OE spec. Even if you max out the VNT-17 you won't threaten any harm to the engine with a stock CR.

And we have a cylinder head install kit if you're looking for one: http://www.idparts.com/cylinder-head-install-kit-a4-alh-p-2331.html

.......and you WILL need to retime everything after the head is replaced.
You should be able to get the static timing close enough for the car to run but should get the final pump timing done by someone who can check it with vcds.

Don't buy a cheap chinese gasket set!

Okay - thanks, IndigoBlueWagon and Maxmoo.

Set timing to tdc, remove belt, turn crank back 90 degrees, now all pistons are halfway and won't hit any valves.
Once the heads back on and cam set to position just bring the crank forward again to tdc and fit belt.

Thanks, Seatman!

Continued here:
http://forums.tdiclub.com/showthread.php?p=5325679#post5325679

I was getting soot in the coolant reservoir. Problem was solved with head studs, so did not have to remove the head gasket.

But I did not have an overheating problem, which for the OP could indicate a water pump failure -- those "local shops" typically do not replace water pumps or any other parts besides the timing belt unless the owner requests it.

Just an FYI for those that only have the dealership as a repair option: look at one of the timing set kits available from the approved vendors, and then get the dealership to list all of the parts on their estimate; make sure they use the exact same parts. It is likely they will not.

Well - nobody was interested in towing a non-op car out of here, so I'm pulling the head.

So now: valve cover is off; valve train looks nice and clean, pretty sure no damage on lifters; basically what you'd expect for 220k miles.

Trying to set the crank to TDC, and I'm not seeing a timing-mark on the flywheel. I'm recalling that I have a G60 single-mass flywheel, not the stock dual-mass flywheel. I don't remember when I installed it, if it had a timing mark.

I have the Bentley; but I'm a bit confused on figuring out exactly what I'm trying to do. (I think I'm confused because if I recall correctly, Honda engines go 4-3-2-1 from the cam side to the flywheel side, and everyone else is the opposite, or is it the other way around? ): I think I want to set #1 to TDC, then I want both valves on #1 closed, (lobes-up), and #1 is the one on the passenger-side, closest to the timing belt. Is that correct?

There is a fresh white-paint mark on the cam; probably from the recent timing-belt job at 210k miles.

The instructions I got from user seatman:

Set timing to tdc, remove belt, turn crank back 90 degrees, now all pistons are halfway and won't hit any valves.
Once the heads back on and cam set to position just bring the crank forward again to tdc and fit belt.

Click to expand...

I think the complete instructions would be:
1: set timing to tdc
2: remove tensioner stud and belt
3: turn crank back 90 degrees (to move pistons)
4: remove cam wheel
5: remove cam caps and cam per bentley
6: remove head studs per bentley
7: remove head
8: (will have head checked by machinist)
9: replace head gasket and head
10: replace cam and caps per bentley (valves at TDC)
11: replace cam wheel
12: turn crank back to TDC position
13: replace belt, then tensioner stud

Is that correct? If I otherwise don't move the fuel pump or crank, then everything should remain in proper relationship, and timing, and should be close enough to start and run? I'm not really sure how I can set TDC of the crank without a timing mark on the flywheel.

If you have the head off , the #1 piston (passanger side) should be all the way to the top. (TDC) When it is , if there is a mark on your flywheel it should be easy to find. If not make sure the piston is at the top of the stroke and mark the flywheel for future reference. I like white nail polish, easy to see and the bottle comes with a little brush, plus the wife never misses it.

With the head still on lobes up is correct the cam tool should fit in the slot in the back of the cam and the pin should slide in the IP hole. At that point even if you don’t have a mark on the flywheel you should be at TDC if you have a running engine. To double check you could pull the #1 glow plug and use a long thin dowel and rotate the engine till the dowel comes all the way up.

I think I can speak with some authority about blown head gaskets, as we have repaired several thousand cylinder heads.

If the cylinder head is removed and the only thing that is done is to cut the head gasket surface, you will build the warp there is, into the cam journals. If the head is warped enough to blow the head gasket, at very least, you need to check the align bore of the cam journals. Otherwise, the cam can be running in a bind. We have seen cylinder heads ruined if this misalignment is not addressed.

Warp can be determined by removing the cam, wiping all oil from the cam journals and the cam saddles. Return the cam to the saddles and try to rock the cam in the journals by pressing on the #1 and #5 journal area. If you feel the cam move in the saddles, it is out of alignment and needs to be repaired. Turn the cam 90 degrees and test at least two more locations, as the cam can also become warped. I would not put a cylinder head back on the engine without fixing the align bore. Problem is, not many machine shops have that small an align boring bar. We do.

We often get the question about head gasket thickness. The measurement for the head gasket has to do with the piston projection; not anything to do with what you may have planed from the cylinder head. If you took off a 2-hole head gasket, that is what you put back on.

You got one of those 'cheep' flywheels... no timing marks.

When the cylinder head is off, you can use a dial indicator to find the TDC location. If you don't have a dial indicator stand, or one you can borrow, you have some trouble, as this is hard to guess. If you work 'by feel' and make several attempts, you might get within a degree or two, but once you get the location, at very least use a paint stick to mark in the timing window on the flywheel and scratch a mark for TDC location. We have a chisel cut especially for this purpose, as you aren't the only one that ever got that CRAP flywheel.

feel free to call if you have any questions.

I do not yet have the head off: just the valve cover (and intake, and etc).

I found the reason why I was confused about piston-order number: there was a thread that confirmed that glow-plugs were numbered differently than cylinders. (and also confirmed my Honda confusion). I'm clear on this now. I'll set TDC and mark my flywheel.

Right now; my assumption is that my head gasket blew, and my cylinder head is "ok". But I'm not going to re-install the cylinder head without taking it to a machinist. I'll have him check the cam journals as well as the gasket surface and valves. I'm not sure what my plan is if the head is not okay. Part-out?

Right now - I just want to ensure that if the head is okay, that when I re-install with a new gasket, that I have timing set properly. I think I understand the process better now, verifying with the IP pin, cam tool, glow plug hole, and cam lobes.

Franko6 who posted above with his contact info is the go to guy for tdi heads and other items also. You can ship your head to him and it comes back perfect.

Thank you, Tdijarhead. I appreciate the compliment.

I also understand need4speed's purpose is to assemble well enough to sell. Although we recommend 'done well', I do understand 'get it running'. The issue with warped heads can turn into a nightmare. We do suggest 'Do it Once and Do It Right', as a warped cam journal can melt a cam to breaking off. At that point, it gets really ugly, as you have destroyed your cylinder head and maybe the block.

Need4speed, you can check the cam for flatness yourself. It's easy to do and requires only that you remove the cam and I forgot to mention, the lifters. Mark the lifters for location and return them to the same location when reinstalling. When the cam is reinstalled, clean, it will be quite obvious if the cam lays flat in all cam journals when you try to rock it. The most common effect is the cam rides high in the #3 journal, if heat warped.

Any questions, I would invite need4speed to call.

Thanks Franko6; your stellar reputation precedes you across the whole TDI world, so of course I trust your word.

I will probably get the head off on Saturday. I have my suspicions on the root-cause of all this, but I'm not going to say until I get it opened up, because it's crazy and I don't want to look like an idiot .

I'll do what I can to verify for myself the cam journal straightness. But there's a machinist in town here who I've dealt with before. I do not know if he knows TDI/Diesels, but his shop does a lot of custom hot-rod work, including sand rails, aircooled vw's and vanagons. (I think gowesty's farms out some work to him as well). I don't really have the budget to pay him to rebuild this head. Or to ship it to you, to be honest.

I don't want to put it back together in "good enough" condition. If it's wrecked, it's wrecked, no sense it putting it back on the road. I could, for example put a head with warped journals back on, with a new gasket, put it all back together, having spent a bunch of hours and about $250 in parts, new coolant, and oil, and maybe it will run, maybe it wont, maybe I can't get it smogged. (costing another $40). Waste of my time and money.

Right now, the main reason I'm pulling the head is to answer the riddle of why it's really overheating. (probably blown head gasket, or... ) - If I can fix it, smog it, re-register it, and sell it, that's gravy. (fantasy-land: find a vanagon/westy that needs an engine, and do a swap, suppose I'd need a winning lottery ticket to make that work. . .).

Franko6;

Well, my suspicion was wrong. I thought it might have been caused by blockage from the plastic bits I saw in the coolant tank a few years ago. But I didn't find anything in the passages. That was a crazy theory anyway.

I got the head off this evening. I removed the lifters, kept them in order. They seem to be in good shape. The cam journals seem straight - the cam does not rock at all, through 360 degrees of rotation. It's in there solid.

What I do see, is evidence of gasket blow-out around the exhaust-side of #2 and #3 (mostly around #3). I don't have a great straight-edge, but I checked with my feeler-gauge, and where the blow-out marks are, I can slip through up to .006", which I guess is pretty bad. Funny that the #3 cam journal doesn't ride high like you say, if the whole head's warped. Or maybe it's just the back-half?

Not sure what to do with it at this point, but I guess I'm going to give you a call on Monday.