Ways to inspect for the VoD block rot before a purchase?

[ramiel05]

Hello,

I'm doing a bit of research for the day in the future that I'll be one of the lucky individuals getting to post "I'm now looking for a Delorean" threads in the sales forum.

I know the VoD and block rot is a pretty big issue to look out for when looking at a car. When the time comes, I expect that I'll be buying a car from a distance and that I'll be arranging some kind of inspection either done by myself or with some help near the car. BUT... Since the VoD is pretty difficult to get to without taking apart a few things, and a seller is not going to want some stranger digging into their engine, are there any other indicators of block rot to watch for? Or is it just kind of a gamble with every deal?

Any tips or experiences would be super helpful.

Thank you!
Mike

[DaraSue]

I had this problem with my car (bought sight unseen) and there turned out to be a lot of rust in the coolant. An unscrupulous seller might flush it before they showed the car but in mine the rust kept coming back despite repeated coolant system flushes.

You can check for coolant pooling in the VOD if you stick a Q-tip on a stick under the intake manifold, or use a borescope to look in there.

[Dangermouse]

Bring a boroscope,

https://www.grainger.com/product/21EN95?cm_mmc=PPC:+Google+PLA&s_kwcid=AL!2966!3!50916684717!!!g!88855184517!&ef_id=UMjvfgAAQOHp8a9S:20180329180019:s

or boroscope attachment for your phone

https://www.walmart.com/ip/Waterproof-HD-2M-7mm-Endoscope-Lens-Mini-USB-Inspection-Camera-with-6-LED-Lights-Borescope-for-Android-Smartphone-PC-Laptop/924102324?wmlspartner=wlpa&selectedSellerId=9869&adid=22222222227083850308&wmlspartner=wmtlabs&wl0=&wl1=g&wl2=c&wl3=196367365898&wl4=pla-314984353131&wl5=9010810&wl6=&wl7=&wl8=&wl9=pla&wl10=115780161&wl11=online&wl12=924102324&wl13=&veh=sem

https://www.amazon.com/dp/B01KFHL17S/ref=asc_df_B01KFHL17S5420784/?tag=hyprod-20&creative=395033&creativeASIN=B01KFHL17S&linkCode=df0&hvadid=198056450525&hvpos=1o4&hvnetw=g&hvrand=14618269385872868811&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9010810&hvtargid=pla-384041321963

[mrpeterman]

When I bought mine the seller had listed that it was leaking oil, which can be a sign. Oil dropping from behind the water pump and down the "front" of the block was the give away for mine. Until I had everything taken apart though it was not clear how bad the issue is. I would say any oil leaks that aren't obvious at first should raise alarm.

[David T]

There is no easy way to check the block to see if it leaked oil and has been repaired. If it is leaking oil it will be pretty obvious. As for coolant leaks, if the intake manifold hasn't been done, or it was done a long time ago, figure on doing it. Same with the hoses and water pump. Figure after 15-20 years it needs to be done. What you CAN check is the plastic screen in the oil filler. If it is melted you can assume the motor was overheated. Other things you can easily check on the motor is the oil, the color, level and condition, the coolant, color, level and condition, the exterior for leaks, the tension and condition of the 2 Vee belts, the upper right muffler bracket for cracks, the idler pulleys for noise, and the general condition of the engine bay. Also check the exhaust manifold for leaks (very common).

[Bitsyncmaster]

The holes you need to inspect are pretty deep and it needs to be cleaned to do the inspection. So unless there is obvious oil dripping I don't think you can inspect it without removing the intake.

[cdrusn]

The first check should be the coolant. If it's the green prestone coolant that has not been changed for 5 or more years there's a good chance of rot. The coolant should have been changed over to the orange Dexcool or better yet, the yellow Zerex 05. The engine is aluminum and if green coolant is still being used and not changed every 2 years then there is likely plenty of damage to coolant passages. Zerex 05 is the only coolant that will keep a Mercedes or Porsche engine from eating itself from the inside out. O.K. let the doubters begin. :race:

[David T]

The first check should be the coolant. If it's the green prestone coolant that has not been changed for 5 or more years there's a good chance of rot. The coolant should have been changed over to the orange Dexcool or better yet, the yellow Zerex 05. The engine is aluminum and if green coolant is still being used and not changed every 2 years then there is likely plenty of damage to coolant passages. Zerex 05 is the only coolant that will keep a Mercedes or Porsche engine from eating itself from the inside out. O.K. let the doubters begin. :race:

There is nothing wrong with the "Good Ole Green Stuff. If it is changed every 5 years it's fine. Nothing is any good after a long time, especially if the motor isn't run. Old brake fluid is also very damaging so if you do find a "sleeper" with old fluids that has not run in years, the chances are you will have a lot of work to do. Be very careful if you decide to use the more expensive and exotic coolants. Some of them do not react well with the older cooling systems. Another problem is incompatibility. If you use an exotic fluid they do not tolerate any cross/contamination so you MUST remove all traces of any other coolant and you can NEVER mix it with any other type.

[ramiel05]

Bring a boroscope,

https://www.grainger.com/product/21EN95?cm_mmc=PPC:+Google+PLA&s_kwcid=AL!2966!3!50916684717!!!g!88855184517!&ef_id=UMjvfgAAQOHp8a9S:20180329180019:s

or boroscope attachment for your phone

https://www.walmart.com/ip/Waterproof-HD-2M-7mm-Endoscope-Lens-Mini-USB-Inspection-Camera-with-6-LED-Lights-Borescope-for-Android-Smartphone-PC-Laptop/924102324?wmlspartner=wlpa&selectedSellerId=9869&adid=22222222227083850308&wmlspartner=wmtlabs&wl0=&wl1=g&wl2=c&wl3=196367365898&wl4=pla-314984353131&wl5=9010810&wl6=&wl7=&wl8=&wl9=pla&wl10=115780161&wl11=online&wl12=924102324&wl13=&veh=sem

https://www.amazon.com/dp/B01KFHL17S/ref=asc_df_B01KFHL17S5420784/?tag=hyprod-20&creative=395033&creativeASIN=B01KFHL17S&linkCode=df0&hvadid=198056450525&hvpos=1o4&hvnetw=g&hvrand=14618269385872868811&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9010810&hvtargid=pla-384041321963

Awesome, thanks for the links! I'm definitely going to get one of these.

[ramiel05]

There is no easy way to check the block to see if it leaked oil and has been repaired. If it is leaking oil it will be pretty obvious. As for coolant leaks, if the intake manifold hasn't been done, or it was done a long time ago, figure on doing it. Same with the hoses and water pump. Figure after 15-20 years it needs to be done. What you CAN check is the plastic screen in the oil filler. If it is melted you can assume the motor was overheated. Other things you can easily check on the motor is the oil, the color, level and condition, the coolant, color, level and condition, the exterior for leaks, the tension and condition of the 2 Vee belts, the upper right muffler bracket for cracks, the idler pulleys for noise, and the general condition of the engine bay. Also check the exhaust manifold for leaks (very common).

Cool, thanks. I'll keep a note of these for my checklist :)

[ramiel05]

I had this problem with my car (bought sight unseen) and there turned out to be a lot of rust in the coolant. An unscrupulous seller might flush it before they showed the car but in mine the rust kept coming back despite repeated coolant system flushes.

You can check for coolant pooling in the VOD if you stick a Q-tip on a stick under the intake manifold, or use a borescope to look in there.

What ended up being the rust issue in your car?

I'm going to definitely buy a borescope, thanks for the suggestion!

[DMCMW Dave]

TThe coolant should have been changed over to the orange Dexcool :

Never. Dexcool is the work of the devil.

The other stuff is fine, or branded coolant from BMW/Mercedes etc. Prestone is now aluminum friendly, but it wasn't back in the 80s.

[cdrusn]

That must by why Dexcool comes standard in Corvette and many other high end cars. The Prestone website says their extended life coolant is compatable with any other
coolant including Xerex G5 yellow made for Mercedes aluminum engines. The devil made me do it.

[David T]

Don't waste any money on a borescope, at least not to examine the top of the block. There will be so much dirt you will not be able to see anything, especially if the voids are full of anti-freeze from leaks. Best case you will see what looks like gold-colored sand, the remnants of boiled off anti-freeze.

[DaraSue]

What ended up being the rust issue in your car?

I'm going to definitely buy a borescope, thanks for the suggestion!

As far as we could figure out, the previous owner had parked it since 1993 with coolant in the lines and there was a bunch of rust and sediment that was congealing around the cylinders and causing it to run hot when going uphill for extended periods of time. Eventually I ended up taking it to DMCCA to have the heads removed and the block cleaned out.

I use my borescope to check under the manifold but since my engine has already been cleaned out there isn't a lot of crud under there. I find that the scope is helpful whenever I'm trying to look at something that's hard to see under normal circumstances (like getting the Pipe of Agony back into its socket after putting the mixture unit back on).