Good engine/Bad engine

I recently bought a car from a repair shop and I was told the car had a 'blown' engine. At that point the car was able to start and run but the top radiator hose had lost its integrity so it was only running well enough to move about a parking lot.

Now that I have the car home I have given it all new radiator hoses, a thermostat, and a gallon and a half of coolant. The coolant still looks green, the oil is a nice golden color, and the temperature gauge hasn't spiked above the middle with the car running for about half an hour and some short runs around the yard. I don't hear any knocking regardless of rpm, it idles smoother than my daily driver, and I can't smell coolant in the exhaust. Although, the exhaust was always white - but for now I want to attribute that to the 24* temperatures.

Other than a compression check what else would you do to verify this engine is still good?

Drive it for a few years and see if it ever acts up.

(No, really.)

check the oil??? look for milkshake colored oil indicating blown head gasket...

Is it loosing oil or water? It is possible to loose either/both fluids out the tail pipe depending on the type of leak. Oil creates a blue smoke and coolant has a sweet smell to it.

Drive it, see if it overheats. If not, score

Sounds like you're in the clear, although it also sounds like you haven't given her a 'proper' drive yet, so I guess it could still be down on performance/lacking compression for whatever reason.

Have you changed the oil yet? Noticed any sediment in the old oil?

Yeah, get it up to temp and see what happens. A BHG could only show when warm and could only be between a coolant passage and the cylinder, never giving the "chocolate milkshake" oil.

I like it how when a car doesn't run the engine is almost universally described as blown no matter what the cause....it's like how any problems with brakes seem to get labeled as warped rotors.

It seems to be from being a Craigslist connoisseur that a blown engine could be anything from a rod through the block to faulty ignition system.

Sounds like you may have gotten a good deal, but only some real driving miles will show if there is a real problem or if was just a bad coolant hose.

Good luck.

Yeah, TJ, and "bad ignition system" can be anything from no gas to a rod through the block.

Dr. Hess wrote: Yeah, TJ, and "bad ignition system" can be anything from no gas to a rod through the block.

I'm looking forward to troubleshooting my 914. The PO said "it has a bad computer". I'm sure that will range from broken mechanical air metering system, to epic fuel leak. Knowing my luck it will be that and everything in between.

To the original poster, take it for a ride. Just bring a cell phone and a buddy willing to push if things go south.

Nitroracer wrote: Other than a compression check what else would you do to verify this engine is still good?

you could install a radiator cap that's had a tire valve stem assembly inserted in it, pinch off the tube to the overflow bottle, and apply about 20psi to the cooling system through the radiator cap and see how long it takes to bleed down.

but i'd drive the E36 M3 out of it. if you've got cell coverage, you've got a ride home....

I did a compression check on the engine this morning, not thinking this is such a healthy engine anymore.

1 - 125psi 2 - 80psi 3 - 80psi 4 - 105psi

The end cylinders had tan/white plugs, the center cylinders were a darker tan. A vacuum gauge showed about 17-18psi at idle which sounds good.

I don't need the engine up and running 100% until spring so I'm thinking about pulling it out and giving it some new bearings and rings.

Nitroracer wrote: I did a compression check on the engine this morning, not thinking this is such a healthy engine anymore. 1 - 125psi 2 - 80psi 3 - 80psi 4 - 105psi The end cylinders had tan/white plugs, the center cylinders were a darker tan. A vacuum gauge showed about 17-18psi at idle which sounds good. I don't need the engine up and running 100% until spring so I'm thinking about pulling it out and giving it some new bearings and rings.

did you follow the compression check instructions exactly? engine was correct temperature, throttle was WOT, etc?

I did not. Did a little reading around while I was at work this morning and Im going to check it properly on monday.

If in fact the compression is that low, that would most likely be why they said the engine is bad. 125 is still ok, but 80 or 105 realy isnt.

Ran a test again with the engine warm and the throttle open. Averaged 110psi on cylinders 1,2, and 4. When I went to test cylinder 3 I had a bunch of air bubble out of my coolant reservoir as I pulled the spark plug, so before hooking up the gauge I spun the engine over and coolant shot out. Found my problem. Now to find a re-build kit that won't cost an arm and a leg. A set of rings, gaskets, and bearings for a 1.8L BP is almost $500!

BHG. It may not need rings, gaskets, bearings, just a HG. You have to pull it apart to find out. Can't you find a junkyard engine cheap somewhere?

Not too many wrecked miatae around here. There is one 1.6L in a nearby yard and I can't find a single usable part on the car. Would any 1.8L BP swap in? I bet I can turn up an escort gt or protege lx for under a grand. Also would a bad HG lead to the low compression in the other cylinders too? The lowest reading on my 1.6L daily driver is in the 165psi range.

www.car-part.com is your friend

Engine 1996 Mazda Miata MX5 1.8 5SPD RUNS NICE 135,826 MILES $500 All Foreign Auto Parts - ARAPro USA-PA(Pittsburgh) 412-782-5580

Crap I just figured out your car is a 1.6L

Your initial compression test readings are diagnostic for a BHG between #2 and #3. As for the "low" reading, it depends on many different things: Cam and cam timing, compression ratio, warm or cold motor, etc. You are supposed to do it on a warm engine, all plugs out, throttle wide open. Write down readings. Add a tablespoon of oil to a cylinder, check it again, go to next cylinder. So 125 PSI in and of itself means nothing.

Check the JDM importers, car-part.com, etc. There's 2 engines within 130 miles of me for $600. There's bound to be some near you. Or just pull that sucker out and tear it down. If the pistons look good and the head looks flat, slap it together with a new HG and see what happens. If they look bad, get a new used motor and go from there.