Overheating

...

I get the same in my Super Beetle. Though, temp gets up to 260F (no clue what that is in C) for about 30 minutes of highway cruising. Mine was timing too far advanced caused by my dist settings. I backed the peak advance off some, but need to re-check and verify.

IMHO, all bugs need an external oil cooler to help when those little under-designed engines can't cope.

On Wed, 12 May 2004 18:31:00 -0700, David Gravereaux ran around screaming and yelling:

very common misconception....the factory oil cooler is more than adequate for a stock engine... JT

Would you consider the following engine not to be stock?

1600cc dual port heads not modified and not using ratio rockers. cam is stock Weber DFEV progressive carb with the heated manifold (redline K1410 kit) dual quietpac exhaust on merged headers mallory unilite (#48) distributor with MSD 6A cdi ignition box, blaster2 coil and gapped to "0.050

Given that the items are external, I claim it as stock.

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Dear David,

You've managed to miss the point.

Normally, only about 15% of the engine's waste heat will appear in the oil. If the engine is fitted with the dog-house type oil cooler and all other cooling system components are in place and functional, the oil cooling system provides about 120% of worse-case capacity.

The point you've missed is that elevated oil temperatures are a symptom rather than a problem. Normally, elevated oil temperature simply means the engine is being operated outside of its designed envelope -- the load is too heavy for the speed or the speed is too high for the ambient air temp, or both. And yes, on a hot day this can occur with just you on-board. The cure is to simply take your foot out. Alas, on a southern California freeway that can earn you a ticket for obstructing traffic, which is why a lot of VW bus owners have learned to fly by night :-)

The root problem is whatever is causing those elevated oil temperatures -- and that could be anything from low tire pressure to a loose nut on the steering wheel :-)

Ever had the measles? Your body temp can hit 105. Dunking you in ice water is a sure-fire treatment of the symptom -- it will bring your temperature down. (Of course, the shock usually killed the patient :-)

Audit your cooling system. Every part is critical. Check to see that the deflector plate is installed on the underside of the HEADS. If running after-market dual-port tin the odds are the gull-wing deflector above the manifold hole is missing. Check your spark plug seals -- ANY loss of air PRESSURE guarantees a loss of air FLOW.

Check your fan belt. And the diameter of your pulley. (Those wunnerful 'power pulleys' guarantee the engine will run hot.) Reach around behind the blower housing and feel every blade in the fan to insure you haven't picked up leaves or other debris.

Check your oil pressure. Elevated oil temp is one symptom of a worn-out oil pump.

Check your brakes, tire pressure and alignment. Low tires, draggy brakes and improper alignment all demand more work from the engine. The car may be doing

65 but the engine could be doing 90.

Ditto for the clutch & tranny. When was the last time you replaced your tranny lube? (Recommended inerval is 2 yrs or 24,000 miles.)

What kind of shape is your engine in? Yeah, I know -- perfect :-) But a lot of 'perfect' engines show up here at the shop with complaints of over-heating. It's not uncommon to find excessive blow-by, indicating worn rings or valves. And excessive blow-by dumps a huge amount of excess heat into the oil. After-market carbs are one the main reasons for accelerated wear of pistons & valves, mostly because of their inadeqaute air cleaners. It only takes about a teaspoon of dust to trash an engine and anyone who has cleaned an oil-bath air filter knows the engine sucks in ten times that much between oil changes. The other failing of after-market carbs is running too rich a mixture, either because of inadequate manifold heating or running a mechanical advance distributor.

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Don't take my word for any of this. Conventional Wisdom, as espoused by the magazines and after-market retailers say that if your oil is running hot you gotta spend some more money by adding one of their sooper-geewhiz oil coolers, with a fan yet, and mebbe one of those ohsokewl thermostatic valves that are guaranteed to leak. And lotsa hose. And fittings. And brackets. And other neat stuff.

Now the oil stays so cool it's kewl. Of course, the root problem -- whatever it is -- is still there, ticking like a time bomb. And when it goes off those wunnerful folks will have some more really kewl fixes you can buy. In fact, the experts have an answer for everything! The only question is, can you afford it?

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Hot oil is a SYMPTOM. The solution is to deal with the problem that produced that symptom. Adding an oil cooler is like trying to cure cancer with aspirin.

-Bob Hoover

Also,very important, check the engine to car rubber seal. If this is dried out,cracked or missing, your engine will suck up the hot air from the muffler and recycle it and cause a vicious cycle of overheating. Had that problem with my 67 . Fred67bug

On Wed, 12 May 2004 21:33:36 -0700, David Gravereaux ran around screaming and yelling:

actually yes i would consider that stock...go out on a limb and call it "mildly upgraded" if you wish...BUT if your engine *needs* an external oil cooler to keep the oil temps down you are looking in the wrong direction....the stock cooling system can an does keep much larger high performance engines running nice and cool...the usual culpirt when trying to chase down overheating problems(whether it be high head temps or high oil temps(which go hand in hand) ) is usually missing or poorly fit engine cooling tin...next on the list is aftermarket tin that usually fits poorly....over advanced timing and poorly adjusted fuel/air mixture are the next things on the list.....engine compartment seal is next....and so on and so on....a properly installed *factory* cooling system is sufficient for 90% of the engines out there on the street(stock and hi-po both).. JT

So if you also bolted on an external supercharger and added nitrous oxide to the mix (also external) you'd claim it was stock? I need to bring you with me the next time I go to get my Jeep inspected so you can talk to the inspectors for me when they start asking questions. Johnnie Cochran, move over! :-)

It is most definitely NON stock, sorry.

You have altered the breathing of the engine in order to get more power (or maybe better fuel economy, or whatever). A major change has been done to the engine, the way it works and breathes.

A stock engine is an angine that still has the same (or equivalent replacements) parts it had when it left the factory. If you replaced the

31Pict carb with a 34Pict, it no longer is a stock engine. It's "otherwise stock, except for the carburator".

Saying it's a stock engine will lead to misconception and misunderstandings. In situations like, when you ask for advice on how to adjust the carb and/or ignition on your "stock" 1600cc dual port engine. Any advice you'd get based on that info alone, would be WRONG.

Jan

....

No, awful! Long story short, one of the main bearings on the crank is shot. At best, she'll get 25psi of oil pressure at highway speed when warmed-up. About 5psi or less at a stop light. But when cold, she'll get

60 ;)

The replacement engine is almost finished and I'll be swapping to it in a couple weeks after the new tranny is ready and numerous other tid-bits are done.

I know I have a pressure problem, but didn't think elevated oil temp would be a side-effect. I feel sufficiently humbled.

What colour are the spark plugs? If they're very pale and lean looking you might try going up a size on your main jet. Also, check your wheels drums aren't binding, sometimes the hoses collapse. Use a good quality 20/50 oil.

--Steve

On 13 May 2004 09:22:08 GMT, snipped-for-privacy@aol.com (Veeduber) scribbled this interesting note:

Bob,

Granted, your experience is far greater then mine, but what I've found is that most air-cooled VW engines are filthy on their exterior. And I mean all their exterior. From inside the fan shroud to the fins on the oil cooler to the cooling fins on the heads and cylinders to the grease and oil and road filth covered transmission and engine sump plate.

The last engine I gave a once over to was so dirty that virtually all the cooling surfaces which are designed to keep things cool were so clogged up that almost no air was getting to them at all. The engine ran hot all the time. The oil, even when fresh, would thin out so much the oil pressure light would come on at idle. After I spent nearly a week's worth of spare (and not so spare!:~) time taking the silly thing apart and cleaning it up and putting it back together it ran nice and cool and is still going strong today. And this was a 36hp engine!

-- John Willis (Remove the Primes before e-mailing me)

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Dear John (and the Group),

Good point.

A friend recently asked me to look at the air-cooled engine on a paving machine (!). I don't know anything about paving machines. Nor those nifty two-cylinder Honda engines. But he'd gone through two engines in two years and it was pretty obvious the Honda guy just wanted to keep selling him new engines at about two grand a pop.

The engine's fins were covered with fur.

Or what looked like fur. It was dust, glued to the aluminum fins with hydraulic fluid.

Actually, it didn't look all that bad... you could brush it off, which they did to the inlet grill every morning. But it would come right back because there was lots of oily vapor getting sucked in by the cooling fan and the machine spends it's life in a dusty environment.

It reminded me of a 40 horse with a leaky oil cooler -- the famous Volkswagen Toaster :-)

The really funny part was the reaction when I pointed out the layer of dust (which makes a dandy insulator). My friend doubted that such a thin layer of crud could be enough to over-heat the engine. But it was easy enough to rig a duct to insure it sucked in only outside air... and without the oily vapor, the aluminum fins stayed clean... and the thing didn't overheat. (Truth is, I think the thing originally came with such a duct... that someone had removed to make it easier to get at the hydrualics.)

Liv & lurn -)

-Bob Hoover

PS -- My personal favorite was the doctor's Porsche and the engine filled with leaves from a Chinese Elm that shaded his reserved parking space. Even when you showed him the cylinders packed solid with leaves he kept insisting they would blow right on through; that SOMEONE must of packed them in there on purpose. Makes you wonder about his diagnostic skills, eh? :-)

We need a song, we fly-by-night bus drivers.

I nominate "Radar Love" for your song.

Hello Bob,

I absolutly agree that hot oil is the symptom not the problem. I have aftermarket tin upper cylinder covers, the rest is original. What do mean with the gullwing tins? The tin at the rear (pulley) side which deflects the air streaming over the upper side of the cylinders to underside and around the rear exhaust mainfold? I'm busy at moment to reproduce the small tins for underside of heads, the where missing on the old heads too. But think this will not gain more than 5 C (41 F), please correct me if I'm wrong.

The rubber engine seal is also new and fits tight arounf the engine. As far as remember the tin has no exessive gaps. but I will dubblecheck in the weekend. I also will try to put some strap, piece of wood, whatsoever over the enginebay insulation. I looks solid and fixed to me, but if the possible is right check the impossible.

As for the engine as stated earlier, it's partial rebuild. All oil channel are cleaned, everything is clean, new cyl./ pistons and new heads. The fan pulley is stock as everything else.

As for the carb, it's an out of the box new Bocar 34-3. Only adjusted idle mixture and speed. All other screws are still seal to get a reference. The manifold heating is working well and also cleaned. Tire pressure and brakes move freely. Tranny maybe needs to be change, have the car just one year and didn't know what PO did.

The Oil pressure is above 65 psi when cold, 56 psi when the oil is 115 C / 239 F at 3500 rpm and 21 psi at idle. When the oil get above 120 C /

248 F the pressure drops to 46 psi at 3500 and 6,5 psi at idle, which is about where the warning light starts.

So I'm still looking malfunctioning. In the weekend I will get another dizzy and fuelpump.

As I wrote, it's a real challenge.

Claus Gerull

Veeduber wrote:

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Look inside the stock DP cylinder-head tin-ware. There is a gull-wing shaped deflector that directs the blower's output toward the exhaust valves.

Making sure the deflector is a fairly tight fit against the fins immediately adjacent to the two upper-middle studs is a standard procedure when mantling a DP engine. Without a well fitted deflector the cut-out for the DP manifold end-castings is little more than a hole through which your cooling air can escape.

Your OP readings look okay. As a test, change to straight 30W and compare the results. No difference is good, anything else is a clue that needs to be checked out.

It would probably be a good idea to rig some instruments to check the stoichemistry of your mixture. Same for your ignition timing and compression ratio. The fact an engine runs does not mean it is running well. There IS a reason for this sort of thing. Odds are, it will turn out to be something you've assumed to be okay... and therefore did not check.

-Bob Hoover

[snip]

Anyone got a picture of these deflectors?

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Your engine is a SYSTEM. All of its parts interact. Problems seldom have a specific single cause but are the accretion of numerous small problems, usually things deemed unimportant by the 'experts.'

The deflector plates on the underside of the heads serve to maintain adequate air pressure in the plenum space ABOVE the heads; the gull-wing deflectors direct the air to where it is needed most; the thermostatically controlled flaps are designed to align with the central fin on the cylinder head so that the densest slug of air from the blower is directed to the hottest parts of the heads... all 'unimportant' details. The failure of any one of them may go unnoticed until you get a really hot day, or climbing a grade with a heavy load. Then you will have more waste heat than the engine can managed.

You're looking for a smoking gun -- a single cause of all your problems. Odds are, you aren't going to find it. What you ARE finding are a host of small 'unimportant' problems, the COMBINATION of which have lead to an episode of overheating. Now the camel has his nose inside the tent because excessive heat carries a legacy of future problems; it's a genie that can't be stuffed back in its bottle.

Most people simply do not believe that such close attention to detail is NECESSARY. Indeed, the archives of this Group contain dozens of messages from idiots saying exactly that when someone having more experience tries to explain why their failure to devote any attention to those 'unimportant' details is the reason thier ride is a piece of shit.

"All my buds say..."

"I've driven for ten years without..."

"NOBODY does it that way!"

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The good dope is in the manuals. The distillation of thousands of man-years of engineering excellence backed up by more than twenty million engine's-worth of experience. Build a few engines yourself and perhaps you can ADD TO that sum-store of knowledge but most of what you read & hear about Volkswagens is from an idiot with one engine's-worth of experience expressing his expert opinion, or an after-market retailer preying upon your ignorance.

-Bob Hoover

On a bug this old you probably have a rebuilt engine. That is likely the case. Most that are purchased around the country do not use a new case. VW considered the engine case expendable. Not using a new case and a compression ratio above 7:1 will overheat your engine and you will be able to do nothing about it. I built myself a pretty strong 1776 and it never overheats even here in Tucson, AZ. It is a function of getting rid of the heat produced as well as not producing too much heat with to high a CR.

After you have checked everything else out that is what you are left with. Check the Gene Berg web site for more information. I followed their advice to the letter and have been very cool and happy with the result.

Dave in Tucson