3.0L engine swap

[FABombjoy]

If you still have the aluminum coolant tubing then a hose collapse is a far lower probability.

Radiator is certainly the lead suspect, either blocked coolant passages or no airflow due to being full of chaff/hair/fluff

[Drive Stainless]

Is the stuff in the coolant kinda like a brown and powdery like cocoa powder? My 3.0L had that going on, too. The Prestone coolant flush stuff works well to get it out; or dishwasher detergent.

[Farrar]

Is the stuff in the coolant kinda like a brown and powdery like cocoa powder? My 3.0L had that going on, too. The Prestone coolant flush stuff works well to get it out; or dishwasher detergent.

Off topic: shouldn't your username be green? It might help other DMCTalkers know you are a parts vendor.

Back on topic: The coolant itself is rather brown-orange, and there does seem to be an extremely fine powder in it which is slightly more brown. I have seen that Prestone stuff recommended elsewhere. Good to see someone with a positive first-hand experience using it. I will pick some up.

[Ron]

Sounds like the rust in the coolant might have caused the thermostat to stick shut...
I'd try draining all I could out then use the flush with the thermostat removed.

[Farrar]

Sounds like the rust in the coolant might have caused the thermostat to stick shut...
I'd try draining all I could out then use the flush with the thermostat removed.

Great minds think alike.

[Andrew]

When I restored Bricklin #177 a couple years ago, I ran into significant overheating issues. While Bricklins are warm blooded to start with, this one was running hot under all conditions and overheating at highway speeds. After my failed attempts at coolant flushes, I finally had the radiator re-cored at a radiator shop (stock Bricklin radiators are NLA and the aluminum replacement is about $700!!!). In summary, the re-core solved my problem 100% It turns out that the old radiator was filled with crud which is probably consistent with the fact that the car had been sitting for about two decades.

While I wouldn't jump into a radiator replacement on your DeLorean, it might be something worth considering if a thermostat, flush and fill doesn't solve your problem.

When you say that your fan shroud is cracked, do you mean the shroud around the cooling fans themselves or the air ducting between the front spoiler and the radiator? I have run 4194 with and without the air ducting (it was missing when I purchased the car) and confirmed that it makes a notable difference in the coolant temp, especially at highway speeds. Under normal driving conditions, with the radiator ducting in place, my cooling fans rarely turn on, and I'm running Hervey's lower temp otterstat switches on both 4194 and 5052. I have also wired my "Cooling Fan Fail" lights on both DeLoreans to operate as a cooling fan running light. The mod takes about 5 minutes and I recommend it highly. Also on 4194, years ago, I added a manual cooling fan control switch in the center console.

You're running a self-bleeder, correct?

Andrew
4194
5052

[Farrar]

When you say that your fan shroud is cracked, do you mean the shroud around the cooling fans themselves or the air ducting between the front spoiler and the radiator?

Not cracked - gone. It was cracked and missing pieces in 2007 when I bought the car. Now there's no trace of it left.

Yes, #2613 has a self-bleeder installed.

I'll try to get some photos soon.

[Nicholas R]

The thermostat will not affect your max operating temp if you're overheating. You'll still hit 250 degrees with a 170 thermostat - or with no thermostat at all - it'll just take a bit longer to overheat.

Coolant just isn't flowing, either due to pump problem or radiator blockage. No need to consider a higher pressure system as plenty of motors are making 2x power with the stock cooling circuit.

Does this car now feature a set of full-length rubber hoses? If so, monitor that the return hose isn't collapsing at higher RPM. Especially of concern since you cruise at higher RPMs in an auto -vs- manual. I know Bill loves this mod but I'd reverse it if it's been done.

I was going to say the same thing. I wouldn't assume that a lower temperature thermostat will have much of an overall effect. For the most part, it only affects how soon your coolant starts flowing. It wont affect temperature at which the engine finds its equilibrium, especially after it's been running for a while. It will buy you more time, especially on shorter trips, but not long term. That being said, a replacement thermostat is still something to consider, simply because its the only designed blockage in the system. If it's not working right, or not allowing enough coolant to flow, you'll definitely see temperatures rise. This happened in my Honda civic recently. After 250k miles and the thermostat was finished with opening consistently. Thermostats are typically cheap enough that it's an easy first thing to change and check off the list.

The fact that you were seeing high temperatures on the highway is very telling as that's when you have the best airflow. You're getting max air moving through the radiator, air over the coolant lines, air across the engine, moving air everywhere. If that's when your temperature is rising, it means you're not exchanging enough heat, primarily between the radiator and the engine. Heat in = Heat out.

Air in the system, Blockages/bad thermostat, water pump impeller condition, radiator sizing; personally these are the items I'd check in the order that I'd check them.

Best of luck! And welcome to Florida! Our year round driving season is pretty awesome, but you've definitely got to be sure your cooling system is at peak performance, especially May-September.

[dn010]

Best of luck! And welcome to Florida! Our year round driving season is pretty awesome, but you've definitely got to be sure your cooling system is at peak performance, especially May-September.

And A/C.

[Farrar]

You all may be right about the thermostat temperature. For an extended road test, Bill drove the car 200 miles from D.C. to Pennsylvania and back, mostly highway driving, and didn't have any trouble with heat. (Pretty sure I posted about it on this thread, but can't be bothered to find the post right now.) And that was with the stock 192-degree thermostat.

My money is on a stuck thermostat and/or blocked radiator because of the mucky coolant.

I blame myself for boiling the coolant, anyway -- I noticed the coolant wasn't green before I left Jacksonville, and I probably should have changed it but I was too eager to get on the road. Similarly, the first time I stopped for gas I noticed it was running about 240 degrees, and I should have done something about it, but again I just wanted to keep driving. The coolant is much dirtier now than it was when I left (in Jax, it was still slightly green and transparent). Obviously I did the car no favors by ignoring it. Oops.

This should probably dampen my spirits, but honestly I am just glad to have a running DeLorean in my garage again for the first time in almost three years. (Engine started randomly dying in the Fall of 2014 & was completely dead by Spring of 2015.) It could be much, much worse... Remember that time my engine caught fire? LOL