Overheated engine @ Road America - Inspection?

#1

Hi Everyone,

First time posting, let me provide a brief intro. My name is Luke Perkowski, I’ve been racing an SE30 this year in the Midwest Region but have been running in GTS since 2011 in an E36. That car is currently down for rebuild, so my friend Ed Kramer and I put together an SE30 that we double duty between the race group and HPDE, it’s been quite the journey this year.

We recently blew up the original engine and put in a fresh one with new bearings, piston rings, refreshed cylinder head, ect. Unfortunately it didn’t last too long, as my co-driver Ed got a little over-zealous with curbing, broke the radiator and didn’t shut the car down until it was severely overheated.

We replaced the headgasket on Saturday night with hope of it resealing but the engine still has low compression, I am sure the head is warped from the temp, but I am curious about further consequences.

Does anyone have experience of the impact of such an overheat on bearings, piston rings, hardware and the moving parts? Is there anything that can be done besides a visual inspection/measurement? I’m guessing everything we reuse is a gamble, but the engine had no more than 2hrs on it, making this a huge shame.

Appreciate any feedback,

Luke

#2

I learned hard lessons in this. Replace your rings. Otherwise you’re probably good.

My engine #5 overheated at Road Atlanta years ago. I’d capped off the throttle body heater hoses with short lengths of hose and then a bolt plugging the hole. The hose in the block developed a small tear. This was before I had a coolant pressure switch installed so the driver had little warning.

Our temp gauge won’t warn you re. coolant loss because as your coolant level drops, it drops away from the sensor probe first.

This was early in my wrenching experience so I had no idea what I was doing. The saga is in a long thread back in ''08 or '09.

The head was cracked. Chuck Baader’s shop welded up the crack for me. That shop would save another head years later.

Precisely like you’ve done here, I asked around on various forums as to what I should do with the bottom end in order to successfully recover from this overheat. I got surprisingly little guidance. It seemed there was darn little info about. The sole piece of guidance I rec’d was “check your rings”.

So I removed each piston, carefully examined the rings, and put each piston back. This was a major production because I’d never done anything so ambitious. The rings looked fine. Which is to say, they looked like I imagined piston rings to look. I’d have to say that I never really understood precisely what “check” your rings meant, but I checked them very carefully.

The head came back, I put everything back together and in the garage the engine, renamed #6, seemed fine. I went to the next event with a big smile on my face and got the car on the track. For the first couple of laps the engine seemed kind of weak, but that went away pretty quickly.

Because the engine wouldn’t run at all. It would run, start, nothing.

It took a while to figure out what was going on. I didn’t have squat for compression anywhere. The problem was that the overheat had killed the rings. They’d lost their springiness or something. So “check” your rings really meant “replace” your rings.

#3

Scott,

Do you have any info on your pressure switch? I now see this as a must combined with the aftermarket temp gauge and perhaps even a water pressure gauge as decreases (leak) and increases (headgasket) would be valuable information.

You are pretty much confirming my suspicion with the piston rings. Especially since the compression didn’t change with the new HG on Saturday (30-60psi) on cylinders we looked at. Although we got the motor running with the new gasket, I decided to park it until we do a full teardown.

Since I’m pulling pistons, I’ll replace bolts and inspect bearings as well. Appreciate any other ideas!

#4

The easiest way to do a coolant pressure switch is to re-purpose your OEM oil pressure switch. Or just buy an extra from Rock Auto. Then find the hose that goes from throttle body to block. It goes into the block near the starter. Pull the barb out of the block. This will take some liquid wrench and a breaker bar. The 12mm thread on the oil pressure switch is a direct fit and the PSI threshold is perfect.

Note that his means you also have to plug the other end of the tbody hose. Do this at the thermostat housing.

Once your engine gets a bit warm, the pressure switch will “open” and your coolant pressure light will go off. As with all warning lights, use some great big light that is bright enough to burn out your retinas and put it right in your face.

#5

A friend of mine overheated an engine when the coolant drain plug in the block fell out. His bottom end survived, but he did crack the head in a cam journal.

2nd on installing a coolant pressure light. It’s saved my engine a few times. Early model car like to have the alternator eat the lower radiator hose.

#6

I hit a big curb at Nashville and thus my radiator hose came in contact with my alternator blades and sliced my radiator hose. I didn’t notice I no longer had any coolant till it felt down on power on the straight and I looked at my OEM temp gauge. I limped it to the pits. I replaced the hose and filled it back up, and I actually ran that engine a couple more race weekends after that weekend. I found out it was down on power considerably. I gave that motor to Fishman when he built my new engine. He did a compression check, and I belive it was down on compression in cylinder 5 and 6. I think all it needed was some new rings to be back in business.

#7

Just want to update with the outcome to keep a record for everyone of the fix.

Tore down the motor and did a full inspection. Replaced the cylinder head casting with a freshly machined one.

The piston rings definitely needed to be replaced. No spring to them compared to the new ones and they were rather brittle. Replaced all the non-reusable hardware, new gaskets throughout and it’s back up and running well. Spent an hour or so doing break-in on the dyno and making some adjustments - just a bit above 150hp/150tq on brand new rings is a pretty good starting point IMO.

I’ll be racing this car at Autobahn and Mid-Ohio (as payment for my hard work :slight_smile: ) after which Ed Kramer will have his comp license and join you guys in SE30. Thanks for all the advice.

#8

[quote=“Lukep” post=78211]Just want to update with the outcome to keep a record for everyone of the fix.

Tore down the motor and did a full inspection. Replaced the cylinder head casting with a freshly machined one.

The piston rings definitely needed to be replaced. No spring to them compared to the new ones and they were rather brittle. Replaced all the non-reusable hardware, new gaskets throughout and it’s back up and running well. Spent an hour or so doing break-in on the dyno and making some adjustments - just a bit above 150hp/150tq on brand new rings is a pretty good starting point IMO.

I’ll be racing this car at Autobahn and Mid-Ohio (as payment for my hard work :slight_smile: ) after which Ed Kramer will have his comp license and join you guys in SE30. Thanks for all the advice.[/quote]
I can’t emphasize enough how important it is to have great big bright warning lights right in your field of view. A close racer buddy who will go nameless because he’s so embarrassed about it has lost coolant twice and failed to notice his pussy coolant pressure loss lights down on his dash. Same pressure warning lights, same failure to notice them, twice. The first time he lost the engine. The second time he dodged the bullet and his engine survived.

I have 2 rows of LEDs on top of my dash so they are right in my field of view no matter which direction I’m looking in the wild action of a race. They are bright enough to burn out your retinas. They are so bright that the car is undrivable at night.

#9

How many lumens are we talking? At some point I’m going to make something more elaborate for warning lights and this would be good information.

#10

I dunno. I bought a bunch of LED lights at local autoparts stores, ebay and Radio Shack. Then I played around with them until I found a solution I liked. Attached is an old pic of the banks of LEDs on my dash. One bank on each side is red for oil pressure, the other bank on each side is amber for coolant pressure.
[attachment=2057]OPWarningLightsFront.jpg[/attachment]