overheating motor !!!!!

[KKV270]

Hi.
Glad to be back after months of being out after an accident.
I rebuilt my motor which had its heads shaken loose from the bang frrom the back.
I split the block but didn't replace anything....and glad to say, cleared off minor oil leaks.
Only hitch I later realized was not having replaced pystons/sleeves back to the orifinal positions... I mixed them as I didn't mark them.

I have done my first "fast 3 miles" and found my motor really heated up in a way I've never experienced.

I torqued all bolts/nuts by the manual.
What could be the reasons behind the heating up??
Advice.

[hercdriver]

Are all your cooling tins in place?
Are your cooling fins in the fan housing? Thermostat attached?
Is your timing correct?
Oil level correct?
Oil pressure correct?
Any metal in the oil?

That's where I'd start.

[KKV270]

Hey Hercdriver,

All cooling tins in place.

Wow!!! Thermostart!!! Please, send me a link on where I can get that unit. Of all the guys I know around, non has this. In our area, dealers stopped getting service deals from owners as it came cheap from garrages around....unfortunately, many garrage guys used to rubbish the thermostart. I have looked for a unit aroun but not many even know what it is

Oil level is ok
oil pressure switch light shows all is well.
Your last one, any metal in the oil?? I can't be 100% but don't mind draining to refill a fresh.

Assuming it is clear, what next??

I'll check on timing once again.

Thanks.

[hercdriver]

What is happening that you think the engine is too hot? It's hard to really help without knowing how hot you're getting. It could be as simple as some oil burning off the cooling tins or it could be the engine is destroying itself internally.

This picture shows the thermostat in its bracket. The top one is good. The bottom one is junk (its expanded when cold). Lack of the thermostat would not cause the engine to overheat. It does move the flaps in the fan housing to help the engine warm up. If the flaps are still installed and closed, then the engine would get less cooling air.

http://www.thesamba.com/vw/classifieds/ ... id=1626756

I asked about metal shavings in the oil, because it would indicate an internal problem. If it's clear, that means there shouldn't be internal damage. I'd also try to see how freely the engine rotates. Does it spin as fast as before the rebuild when you start it? Again, if the engine does want to turn over easily, it maybe binding inside. Which would cause it to get hot. You mentioned swapping cylinders and rings. If they are tight it would cause some heat. With any luck they'll wear into place. But they may also score the cylinder walls. A compression check would help diagnose a ring problem.

If it has been running hot, you should check your valve clearance (especially #3 exhaust vale). Make sure the engine is nice and cool before you check. I like to let the car sit overnight before I check.

At this point you know this engine better than anyone. Be methodical about tracking down possible culprits.

[Blue Baron]

I like to use the thermostat and flaps whenever possible. (A VW mechanic friend gave me a bunch of spare thermostat parts recently that others threw away.) But I'd say unless you live in a cold part of Kenya, you can get by without it.

[h~moto]

All cooling tins in place.

Did you remember to reinstall the deflector plates that grip onto the cylinder head studs. They are attached below the two cylinders on each side of the engine. They ensure that the air is directed around each cylinder.

[KKV270]

The reason I say the engine is overheating, on a very short distance ride, (6 miles), I could barely hold the dip stick/alternator/engine parts...plus the decklid was hot.
I admit, I took it very fast and loaded it much at some point...but never have I felt such temperatures...yet done 90+ miles nonestop.

the initial tests while on the ground didn't result to any overheating. I then, before mounting back, confirmed torques (after an hour of running the engine) & redid the valve clearances.

1. I will check the valve clearances once again.
2. Timing is ok.
3. Engine rotates nomal with equal resistance as earlier.

I thought about the rings and cylinders and thought probably that what you say about them wearing intlo place might be part of what is happening.

4. I placed back all tins and deflector plates (other than one deflector plate that I aquired the car without.

I will check on the valve clearances then report back on the results after a few more drives over the weekend. Thanks for the valuable contributions.

Hercdriver, just curious, why exhaust valve #3?? What about it demands more attention?

Cheers guys.

[hercdriver]

#3 cylinder gets the hottest due to the cooling air flow and the location of the oil cooler. Of the exhaust and the intake valves, the exhaust valve gets the hottest. If your engine is overheating to the point of damaging the cylinder heads, you'll see your valve gap change first at the #3 exhaust valve.

[KKV270]

Hi.

EUREKAH!!!!!!!!!

1. Major problem detected. - Tight exhaust valve clearances.
2. Leaking oil cooler at the gasket seal point.

(I feel like I just have to explain this "blanderous" errors....

On running the engine for an hour on the floor during the tests, I left it to cool for slightly above an hour....after which I re-torqured all bolts/nuts.

Having had to remove the rocker-arms to torque the heads, I re-did the valve clearances.....but I think that might have been too soon. Interesting thing is, it's only the exhaust valve clearances that were all tight.

As for the oil cooler, I noticed a slight leak initially but "thought" it was a push-rod tube.....which I, to a big shock, saw a major stained side as I was getting to drop the engine to fix.

Now I think I'm good to go. I haven't yet cranked (starter issue pending) but will drive off and definitely post the results.

This is soooo exciting.

[KKV270]

I did a 40 miles trip but still heating up. Good news is, it isn't as hot compared to what I experienced on the 6 mile trip.

Well, I will keep on and see hoping it will cool off with time.
Question! Say were it to be the rings seating into place, how long does this take (whilst still heating up the engine above normal)??

[hercdriver]

I would be concerned. It may be the rings, but they should have seated by now. (Unseated rings would have smoke coming from the exhaust. Before the rings seat themselves into the cylinder wall, oil is able to get between the rings and the cylinder wall and migrate above the piston. From there it is burned with the fuel and produces smoke in the exhaust.)

Keep checking your valve clearances. They are telling you about the consequences of overheating. They are not the reason for overheating.

Any other symptoms? Like rough idle? Popping noises during deceleration?

Check the easy stuff....
timing
cooling tins
oil pressure
rags/ debris in the engine compartment/ fan housing
low oil level

If it still runs hot, I'd pull it out before it ceases. Then check your....
end play
Oil cooler - clean it
cylinder heads re-torque
air deflectors
fins in the fan housing

Good luck we're pulling for you.

Here's a diagram for cooling tins.. check for #4 on both sides (it's the air deflectors mentioned above).

[KKV270]

hey,

Thank you for the clear troubleshooting tips.

I will pull through. Thanks for the support. I will post the progress.
Regards.

[Blue Baron]

Interesting thing is, it's only the exhaust valve clearances that were all tight.

That's not a good thing. It's an indication that the exhaust valves are stretching. I assume you replaced all four exhaust valves.

You need to keep a close eye on the clearances. Stretching valves can be a sign of inferior exhaust valves. If the problem persists, there's only so far they will stretch before one breaks off, and odds are that it will be No. 3 cylinder.

I'm in the same boat. I have a glorious running 40hp in my '63, and the exhaust valve clearance keeps tightening up, and I'm in complete denial about it.

[KKV270]

Hi Blue.

(for starters, as I still learn more on VW Bugs, the "quote" function would have come in handy....but I keep getting it wrong!!! well, for another day )

Remember, I didn't replace any part but in stead, accidentally mismatched sleeves/pystons (that is if I didn't, by chance, get them all back to their original positions)

I have done about 90 miles since the last post.... the engine is growing cooler.

Thanks for the note that valve clearances are not the reason but a sign to something amiss.... however, say I did the clearance wrong, wont that contribute to overheating?

I will do 2 proceedures; oil change and a compression test, then feed you on the results henceforth.

Thanks guys. You guys have been a source of wealthy info that has turned me into a confident and proud VW owner.

Cheers.

[KKV270]

Hi.

I have good news. I found a major culprit...My distributor had a small issue that contributed to problems. My condensor wire had peeled off part of its coat and was short-circuiting against the block. This was a subtle thing....but had recently become more aparent when I stalled suddenly (a problem coupled with a lack of functional starter).

On checking the firing spark from the point, I realized a false spark coming from the other exposed area. I believe this contributed to poor timing....thus overheating.

Also, recently learnt from Chris of classicVWbugs from one of his posts on the implications of lacking the engine rubber seals (which i don't have....plus I compounded the matter by connecting the heater channel exhaust connectors and have no connecting pipes from the dog-house....so all heated up air just breathing into the engine compatment....... I can't believe.... it's like I just did all the "Do Not's".

Wow.... I guess this explains a lot.

Having said all this, I will undo my errors and make further observations.

Cheers.