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Discussion Starter #1
Hi guys, I just completed a motor swap and my car is running way hotter than it should be. I have an '86 Scirocco (it was an 8v to begin with) which I put a '91 Jetta engine in. I only swapped the block and the cylinder head. All other components were from the previous engine. The reason I replaced the engine is because the oil was mixing in with the water and it didn't look good. Now the temp needle is 3/4ths the way up the gauge (and the light is blinking, too) after driving it for 5 minutes. It seems to be leaking water in a couple places, could this have a large affect on the engine temp?
Thanks in advance,
Ben
 

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Re: 8V overheating...how to fix? (RoccoRacer)

Maybe you could check the water pump/thermostat and see if it's flowing right, check hoses for pressure, or some blockage of flow.
Good luck
 

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Re: 8V overheating...how to fix? (luisgp)

if you have not replaced the water pump on that new engine chances are this is your problem
 

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Re: 8V overheating...how to fix? (RoccoRacer)

1. Water leaking in a number of places: Coolant system requires 15 PSI or less to do a god job (the cap blows off excess over 15 psi). If it's leaking it ain't cooling the best it can.
2. Watercooled motors can be refilled but still have air pockets in the block. It's a good idea to refill into the block via the top rad hose 1st.
3. Some folks drill one or two small holes in the plate of the thermostat (which in this case may be stuck shut btw) to allow air trapped on the backside to exscape.
4. DId you put coolant in the mix or is it just water? Is it all coolant? 50/50 is a good place- folks can use down to 30 coolant / 70 water depending on heat and cold in the area.
5. Is your thermo switch working/ plugged in? is the Rad fan comming on?
Lets us know, hth
TBerk
 

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Re: 8V overheating...how to fix? (TBerk)

91 Jetta motor? What is the motor's code? Look between the head and block near the distributer. If it's a 10:1 high compression motor you havent mentioed wether you are accounting for a knock sensor, and/or wehter the timing might be off on this.
Oh, oh wait: The motor needs to have the fuel to air ratio set, running too lean = overheating.
There, that's a lot to work with.


TBerk
 

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Re: 8V overheating...how to fix? (RoccoRacer)

If the oil was going in the water like you say then you could have a blocked radiator.
 

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Re: 8V overheating...how to fix? (Vdubs)

Is the engine really overheating or is the temp gauge just reading hot?
Did you install the original sender for the temp gauge or did you use the one on the new motor? They may be different giving you a false reading. I alway swap the original senders into new engines. I have a tire pyrometer that i check engine temps with, but any sort of thermometer can be used. You want to check the temp of the coolant coming out of the engine (upper radiator hose). Id be surprised if it was >225 after only 5 min of driving.
On these engines, the thermostat is on the bottom (at water pump) This makes filling a cold engine difficult, unless you fill it through the upper radiator hose. After you fill it, let it idle for a while until the thermostat opens and then top it off.
 

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Discussion Starter #8
Re: 8V overheating...how to fix? (left turn scirocco)

Thanks, guys!
I have a lot of stuff to check up on tomorrow, I guess.
So far I've been using just water (and a little bit of Simple Green)...the temp here right now is 70's. All the water leaks have been fixed.
The rad fan comes on, but they have two settings, right? It'll come on when I'm cruising down the freeway and the temp will stay level, but when I'm accelerating the temp gauge goes up quite a bit.
It is a 10:1 comp engine, and there is a possibility that the timing may be off, I'll have to check that, too, and I'm not sure what the fuel to air ratio is at, I guess it could probably be turned down.
Only the block and cylinder head are from the Jetta...everything else is from the origional Scirocco engine (except a few new hoses and now a new oil cooler).
Thanks again!
Ben
 
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