Slow_sevens

Newbie here. Please excuse ignorance. Just installed new below radiator oil cooler and lines, and was working in a sloping driveway. Once cooler was in but before filling with oil we rolled the car backwards down the driveway to level ground. My kid was at the wheel and accidentally left first gear engaged as the car rolled back. There was enough slope for the car to roll even though in gear. As the car rolled backwards it peed a line of fluid down the driveway. Checked under the engine and saw fluid dripping from rear edge of oil pan.

We assumed oil pan leaking oil. But a day later the fluid stains have gone from driveway so must have been something that evaporates? We were working on the vehicle at dusk so don’t have a good read on the color of the leaked fluid.

Am I correct that if a leaking fluid evaporates to the point of completely vanishing from driveway concrete it is not oil?

And what could cause a FB rolling backwards in first gear, ignition off, to squirt fluid that would drip from the oil pan area?

Thanks!

7aull

iTrader: (2)

Welcome!

So with the engine engaged as it was rolling back, presumably it was rotating inside, and therefore moving fluids around to some leak point.
Oil does not evaporate. Note does coolant. Any chance the car has AC and that was the leak? Maybe off the AC compressor.
Gasoline would evaporate - did it smell like gas? Loose fuel line fitting at carb?
Others will jump in here...

Stu A
80SG
AZ

Slow_sevens

This stuff is fun. Hard. But fun. My 16yr old kid purchased a FB couple of months ago. He is totally in love. Car is drivable but with the usual 40 yr old car problems.

Convinced myself it was not oil leaking so refilled with oil and ran the engine. New cooler and hoses holding just fine. Got under the car with a flashlight and found a drip. Not gushing like it did when rolled backwards, but from the same place. Definitely coolant as bright green. Checked radiator, expansion tank empty and coolant down an inch below neck of radiator so definitely know what the fluid is.

Drip is rear edge of oil pan. Cant see well enough above that point to see if trickling down from somewhere higher. Have a contact with a lift so going to get the car up in the air this week and see if we can trace leak. Any hints of what to search for appreciated. (Learned the term ‘freeze port’ this afternoon!)

KansasCityREPU

iTrader: (9)

Check the heater hoses on the back firewall. There is one that connects to be rear iron just below the oil filter.

mazdaverx713b

iTrader: (91)

Knowing what year you have and if the car originally came with the front mount oil cooler can help us narrow down the issue. The cooling system had minor variations over the years with the addition of the water to oil top mounted oil cooler in late 1983 and the front mount oil cooler returning in 1984 on the GSL-SE.

The leak is likely at the rear iron on the driver's side under the oil filter. The coolant hose there gets soft from oil seeping on it from oil changes and bad oil filter pedestal o-rings. Once it becomes soft, it can develop a tiny tear or blow out completely when the system builds pressure. I would inspect that area first.

Slow_sevens

It’s an 81. Oil cooler below radiator. Cooler was cracked. Was replacing it with a CSF 8066 and had just finished when The Kid’s backwards in-gear roll revealed the coolant leak.

Will clean off the gunk below the oil filter this week and see if I can see a trickle leading down to the oil pan drip.

7aull

iTrader: (2)

Check to make sure its not a coolant leak at the Intake manifold. There is a cooling circuit off the water jacket that runs coolant into the intake mani. One for the two O-rings (2 ports, 1- ring each) hasn't failed. Fairly common actually. Mani needs to be pulled away and new O-rings (and, obv, a gasket) installed. Sometimes this also shows as coolant collecting on the top of the motor where the mani meets the block. But can see where it could easily weep then find its way down the block and around the oil pan or tranny and make that look like the source...

Stu A
80GS
AZ

KansasCityREPU

iTrader: (9)

The factory oil cooler has an internal thermostat with bypass. This ensures the oil is warm. This may not be an issue for you but just be aware. I used an external Earl's oil t-stat with my aftermarket oil cooler.

Slow_sevens

Did some research on the thermostat. Decided to try it without, as we are in California and really dont see cold weather driving conditions and The Kid lets the car warm up before driving. And frankly was beginning to mount up in cost! Also installed a oil temperature gauge monitoring right below the oil filter as wanted to make sure our new setup was doing its job. (Installed is a lose word, the actual gauge we fed through the firewall and I hold it in my lap in the passenger seat). Only one drive so far, oil temp sat around 160 - 165 under gentle driving conditions. Very much new to all of this, so let me know if I made any bad moves there.

LongDuck

You need to put the Thermostat back in. The way it works is that the spring holds the plug over the Water Pump outlet which also seals it off from recirculating coolant through the block. If you remove the Thermostat completely, there's nothing to direct the coolant from recirculating and forcing it through the Radiator instead. This will result in overheating of the engine without you knowing it's that hot if any of your temp sensors are inoperative.

Put the Thermostat back in.

Slow_sevens

LongDuck... At the risk of showing myself as the total Newby that I am... are you talking the thermostat for the oil cooler or the thermostat for the coolant? Asking 'cause you mention water pump and coolant. Or maybe as a Newby I dont yet understand how not having an oil cooler thermostat has a knock on effect on the water coolant system? Want to be sure I dont cook The Kid's engine!

LongDuck

Yep, you're right - I was referring to the COOLANT Thermostat mounted to the Water Pump. I haven't checked back on this thread in a few days and picked it up reading about your choice to remove the (oil cooler) Thermostat, and you didn't specify in the post above mine.

You should be fine to remove the Oil Cooler Thermostat, but recognize that Mazda put it in the flow path for a reason, and that's to ensure proper lubrication at startup until the engine heats the Oil enough to flow well through the entire system. You may want to consider a lighter cold weight viscosity oil going forward, but I'll defer to the guys who have done so.

Slow_sevens

No worries. Totally see that my terminology got vague as the posts went along. Agreed, when Mazda designed the engine they added an oil cooler thermostat for a reason and have adding one on my do-list, looks simple enough to add between the out and return lines in an H pattern. Just wanted to keep the initial install simple / less expensive as replacing the oil cooler and lines was The Kid's first major repair on his first car and wanted it to be reasonably fast and simple so he would not be discouraged. Right now its a hot mess love affair between his and the car, and want to keep it that way. Nothing like a 16yr old and a 2 door rear wheel drive stick.

Just noticed your 240k. The Kids is 165k on original engine, and thought that was loooooong for a rotary. I hear rumors on this forum of unicorn engines that just keep going.