overheating TD Vanagon

[witoke]

Okay, here's the question:

82 Vanagon diesel that has been converted with freshly rebuilt 1.6TD with rebuilt stock injectors, rebuilt injector pump, new water and oil pumps, rebuilt radiator and 5 speed transmission. About 1500 miles on the rig so far.

Engine overheats on long-ish low grade climbs. It is perfectly okay in town and if just cruising around town, EGT's may not get above 800F and temp gauge is constant just above half. On level highway there is no problem cruising at 70mph with EGT's still around 8-900F. If I get onto hill things change dramatically and the EGT's can easily hit 14-1500F. And no, I don't let them stay there. When that happens the engine is also getting up into the top of the temperature gauge.

No IC, no boost-gauge, no oil-cooler (yet), supposedly absolutely stock pump; no smoke unless under heavy load with EGT's climbing when I get some haze. Mechanic has checked thermostat and the cooling system and pronounced it good.

I'm wondering if the turbo is bad, mostly because it's the only thing that is original but any input from someone with more experience would be VERY welcome. It feels like it builds boost pretty easily in the low gears but at higher speeds does seem to struggle a bit to maintain speed.

thanks for any ideas anyone can give.

[jimfoo]

An IC and turned up boost will help EGT's, and on my engine, EGT's seem directly proportional to water temp. An oil cooler will help as well, just don't put it in front of the rad.

[the caveman]

I'm pretty sure TD's have either a larger fan or more powerful fan motor or 2 speed. I would look to see what came stock compared to a NA vanagon diesel. You also need an oil cooler. I wouldn't bother with the stock one that fits between the oil filter and flange, i would put a larger capacity one in the airstream. They also came with an after run pump to help circulate the coolant ,but that probably won't help in your specific problem but i would also look into installing one of those. Perhaps the rad itself was larger, but how old is it. Maybe time to change. I realize that if you are having fueling issues it will affect all this, and upgrading the cooling system is really a band aid for the real issue, but you will have to check into it.

[Baxter]

early vans have crap radiators, really small, thin affairs.
I would swap to later plastic hoses (still available from VW in the UK, I know as I fit the fuppin' things all the time and have healthy stocks!) and a later radiator.
To do this you need to rape the upper mounting bracket from a later van and weld it in, not rocket science and swap to the later lower rad mounts.
Larger bore pipes means coolant travels slower, means it hangs around in the radiator longer, means it get cooled more.
TD's in Europe didn't come out till 85, when they did they had a different cab floor to make room for the 500w radiator fan!!
When fitting aftermarket radiators I find that they don't cool as well as the OE ones do.
Aftermarket thermostats we get here are generally crap, we buy from VW.
T3 TD's also, as stated came with an auxilliary water pump, switches on at 104°c, they only really work when the engine is off, or when it's toast!
We have driven early Diesel vans with TD's in, and they do get toasty, we've driven them with AAZ's, and they get toastier even in our "moderate" (reads - piss poor) climate.

pop an 1/8th hole in the stat and see if that drops it down a bit, bit of a bodge but sometimes when everything seems right it can do the trick.

[the caveman]

see the guys in europe [okay, okay the UK] know more about these models then we do.For vanagon,transporter ,T25 stuff i also check out the Club 80-90 forums

[witoke]

thanks Mr. BY and others,

it sounds like this is a physical capacity problem with the radiator that VW had dealt with on the newer models. I can certainly get the bits to get it done properly and maybe that will be enough. The original rad that is on the van is certainly thin. I suspected something along those lines because it always seems to run a bit hot.

I do plan to get an IC and add a remote radiator/fan type oil cooler but that is going to require surgery to relocate the battery so that I can get cool airflow from the side vents for the air intake on one side and for the oil cooler on the other. But first get it running properly and then I will start to play with the other stuff

BTW the aftermarket thermostats we get here are crap also.

Thanks for the input, this list has been a great repository of knowledge.

[myke_w]

hold on before you change anything.. overheats meaning what exactly?

tell us more about the symptoms..

does it boil over?

goes hot on gauge?
 in Vanagon D's thats quite normal especially on grades. The coolant cannot get to the front of the vehicle get cooled and get back fast enough to drop heat as well as a car.

I had a stock Vanagon D copper core radiator (albeit rebuilt) in my TD rig and it was great, the biggest problem is that if the level goes low (or you didn't bleed the air out) the fan switches on the radiator cant activate (they sit up high) but frankly, if the van is moving they shouldn't ever really run unless you're in a very warm climate.

Oil temp was only a problem when cruising above 70 for long intervals in 70+ weather

tell us more

[Vanagoner]

Here is a link to what looks like a high quality electric coolant pump which can be used as a booster pump.
http://www.daviescraig.com.au/main/display.asp?pid=46
I haven't tried one, but it is on my wish list.

[myke_w]

actually td v-gons came with a pump like that factory. It's the same as on any 1.8t and other hot running models.

[witoke]

After getting a number of conflicting replies from this and another forum I decided to find out exactly what was going on when the temp gauge hit the end of it's range and the EGT's were going nuts.

I bought an IR thermometer and did some recording of temps. Turns out that the van is NOT overheating. When the gauge hits 3/4 the coolant temp is only in the 80's C and the temp drop across the radiator, measured at the feed and return lines in the engine compartment is 6 degrees. It is either the gauge or the Jetta temp sensor that is wrong.

At close to the top temp mark the first stage of the fan kicks in and the coolant is in the 90's. With the fan the temp drop across the radiator is 16 degrees. Max oil temps were 105, measured at the filter and the oil pan.

But, at this temp level, achieved going up a freeway hill the EGT's are hard to keep below 1400 F without dropping speed down to 50mph or so. If I try to keep highway speed by using more throttle, the EGT's go instantly into the 15-1600 range.

So, am I correct in thinking I need less fuel or more boost or both? I am going to add a boost gauge as well  as oil and coolant temp gauges to try to keep an eye on things while I get this sorted out. Can anyone recommend a primer for this sort of problem?

Ultimately I plan to add an oil cooler and an oil cooler, once I find the time to figure out how best to shoehorn them into the Vanagon engine compartment. But I do want to get to the bottom of the EGT thing before I burn a hole in a nice shiny new piston!

[jimfoo]

Yes, more boost, less fuel or an IC will help EGTs. Timing affects it also.

[gldgti]

if you keep adding too much boost the EGT's will rise anyway.... when its compressed so much without an intercooler, your inlet temps will be over 100deg C easily.

[myke_w]

what are you doing with the Blow Off Valve? leaving it open to operate will spike egt's you want it all the way shut.

Do you have a boost gauge?

How much boost are you seeing?

is your wastegate working?

[witoke]

Myke, going to get a boost gauge today. I'll post the results and check the BOV and wastegate as well.

[myke_w]

if you havent blocked the BOV and have blocked the wastegate, your boost air will go right out of the BOV and then all that will be left in the chamber is fuel. this will spike egt's beyond all recognition.

You can block your BOV by removing the screw in the top, getting a 15mm long 10mm head bolt and replacing the small spring in the bov with it and then putting the screw back in snug.

A boost gauge is a must have so I'm glad you are going that route. On a k14 turbo you really don't want to go more than 15 psi, after that it starts getting kind of risky.