m52 swap causing leaky radiators

[luckysnafu]

I just found a leak in my 3rd m42 radiator in my m52 swap (OBDII). The first two radiators I put in were used and leaked in the middle of the fins. The third one that's in now is brand new and is leaking at the bottom passenger corner. The car will overheat if left idling, it went up to 3/4 in 15 minutes in my driveway tonight after I got home from work. All 3 radiators were e30, none were e36 m42.

What could be causing me to bust 3 radiators?

Also of note:
My engine idles very low, 450-500 rpm, and shakes my car like crazy. I haven't been able to figure out why this is happening but I've done the following:
Replaced spark plugs
Cleaned MAF (idle does NOT improve unplugging)
Cleaned ICV
Plugged all vacuum leaks
Unplugged front O2 sensors (rear ones removed) and no change in idle

Engine pulls hard and does not hesitate/bog down once I get above 1k.

I installed a new water pump, thermostat, housing, hoses, etc. when I swapped the engine.

Any help would be greatly appreciated.

[jlevie]

If none of these radiators leaked immediately after installation I'd suspect a head gasket leak or a cracked head that is over pressurizing the cooling system and causing the radiators to fail.

[M-technik-3]

Agreed, pressure check the system.

[luckysnafu]

Damn, not what I wanted to hear. Makes sense though. When I installed spark plugs the other night when I took off the oil cap there was condensation on the cap and some brown milky stuff on it. Was hoping it was residual from the engine sitting for a few months before the swap.

Guess it's time for a new head gasket...

[M-technik-3]

It could have been residual moisture in the oil but just check the system pressure. I believe Advanced Auto has one of those tolls as a loaner.

[luckysnafu]

I should have time this weekend to get my hands on a pressure tester.

[drumad]

You need to check if all 6 cylinders are firing. The shaking could be an imbalance from a dead cylinder or two.

[jlevie]

Damn, not what I wanted to hear. Makes sense though. When I installed spark plugs the other night when I took off the oil cap there was condensation on the cap and some brown milky stuff on it. Was hoping it was residual from the engine sitting for a few months before the swap.

Emulsion under the oil fill cap, especially in the winter, doesn't necessarily mean a head gasket leak. It can be just a sign that the engine isn't being worked hard enough, long enough, to boil off the condensates.

A DIY test for a leaking head gasket that is pressurizing the cooling system is to completely bleed the cooling system, drive the car for a bit, and re-bleed. Release of a significant amount of air then or during a subsequent bleed is evidence of a head gasket leak. Another check is to see if the hoses are hard and under pressure after the engine is completely cold.

[ExViTermini]

One really quick very good easy way to check headgasket is remove the expansion tank cap. Take a cup of water and place the overflow hose from the expansion tank in it. Start the car and hold your had over the cap hole on the tank.

If you keep seeing bubbles float out in the cup of water with the overflow hose in it, your SOL.

[dakon]

One really quick very good easy way to check headgasket is remove the expansion tank cap. Take a cup of water and place the overflow hose from the expansion tank in it. Start the car and hold your had over the cap hole on the tank.

If you keep seeing bubbles float out in the cup of water with the overflow hose in it, your SOL.

How would he do this with an M42 rad, with a built in expansion tank?

[ExViTermini]

How would he do this with an M42 rad, with a built in expansion tank?

Your right... I haven't looked at an m42 rad in quite some time, had to google it to remember what it looks like and from the pics I found I don't really see a way.

Sorry I wasn't able to help you.

[luckysnafu]

Checked under the oil cap last night. There weren't any water drops or milky looking liquid.

So the general consensus is to do a pressure test of the cooling system?

[luckysnafu]

Good news: Fixed my idle problem. The oil separator vacuum line to the dipstick tube was just hanging. I plugged it up. What are others doing with this? Oil catch?

Bad news: Still have overheating issues. Didn't have a chance to test the pressure, hope to pick up a tester tomorrow night.

I tried testing the head gasket using this - http://www.napaonline.com/Search/Det...006_0282450468

I wasn't able to get a good amount of air out of the radiator. As the engine would heat up antifreeze would come out and ruin the test.

- Upper radiator hose only gets hard when the engine temp is over 1/2. This hose gets soft after the engine cools down.
- When I rev the engine up the engine temp (cluster) goes down.
- Heat in the car is only very hot when the engine is revving. Not hot at idle.

Engine overheats quickly after it gets above the 1/2 mark on the temp gauge.

[SpecM]

Sounds like a water flow issue... water pump?

Sent from my Ally using Tapatalk

[Boosted E30]

Is your lower rad hose hot when the engine temp is up around half or when its overheating? If its still cold then your thermostat is not opening and you may still have air bubbles in the system or a faulty thermostat.
Also you can pull your spark plugs and see if any of them are clean/washed off, this will indicate a possible coolant leak into that cylinder.