Roadrace d24 problems

[Dirty Duc]

So, after the race, one of the wise and benevolent Lemons judges remembered that he had seen a D24T 760 in a junkyard in Phoenix the Thursday before the race. We went up there today and yanked it. It's got the cruise control whirligig, but the vacuum pulling thing is no good any more. I left the power steering pump, AC condensor, and trans.

[v8volvo]

Nice find, the turbo motor will definitely be an improvement as a starting point. Someone might want the cruise control fixtures if you don't use them (could swap the non-cruise setup from your old engine over). Particularly folks in Europe where most cars were for some reason sold without cruise like to retrofit them.

Sounds like you got all the life your old motor was able to give with some field engineering, impressive it was able to get back on the track after all that. But it sounds like its days are numbered if it started to crack the block. Block cracking around the head bolt bosses was a well known problem with the early 1980-only D24 engines that used 11mm head bolts (with a 6pt inhex head rather than the triple square 12pt head that the later engines with 12mm torque-to-yield type bolts had), but pretty rarely seen on the 1981 and later engines produced after they upsized the hardware. I wonder if you have the early motor? What type of bit do the headbolts take on yours? Or maybe your usage demands just found the limits of the equipment either way.

Most of the time on these engines a gradual failure of the headgasket first causes overpressurization of the cooling system without any poor running symptoms, then later can lead to coolant intrusion into the cylinders. But a volcano of coolant out of the radiator cap when the engine is under load is the first sign, even if the engine still starts and runs fine.

[Intercooler-BurnzZ]

Originally Posted by Dirty Duc

So, after the race, one of the wise and benevolent Lemons judges remembered that he had seen a D24T 760 in a junkyard in Phoenix the Thursday before the race. We went up there today and yanked it. It's got the cruise control whirligig, but the vacuum pulling thing is no good any more. I left the power steering pump, AC condensor, and trans.

Good job!
Saved a couple of nice parts from it's damned & useless destination of corrosion & give a second life!

[Dirty Duc]

Originally Posted by v8volvo

Nice find, the turbo motor will definitely be an improvement as a starting point. Someone might want the cruise control fixtures if you don't use them (could swap the non-cruise setup from your old engine over). Particularly folks in Europe where most cars were for some reason sold without cruise like to retrofit them.

Sounds like you got all the life your old motor was able to give with some field engineering, impressive it was able to get back on the track after all that. But it sounds like its days are numbered if it started to crack the block. Block cracking around the head bolt bosses was a well known problem with the early 1980-only D24 engines that used 11mm head bolts (with a 6pt inhex head rather than the triple square 12pt head that the later engines with 12mm torque-to-yield type bolts had), but pretty rarely seen on the 1981 and later engines produced after they upsized the hardware. I wonder if you have the early motor? What type of bit do the headbolts take on yours? Or maybe your usage demands just found the limits of the equipment either way.

Most of the time on these engines a gradual failure of the headgasket first causes overpressurization of the cooling system without any poor running symptoms, then later can lead to coolant intrusion into the cylinders. But a volcano of coolant out of the radiator cap when the engine is under load is the first sign, even if the engine still starts and runs fine.

The "old" motor had 12mm bolts swapped to head studs. I think it's most likely that the overheating incident at the September race caused the initial damage, and then it just got worse over time.

I wasn't getting a volcano after swapping heads and head gaskets after September, just the earlier sludge in the water. That got progressively worse as presumably the crack worsened. I'll likely keep the "old" motor assembled as an emergency spare until I can get ahold of another. Better an iffy motor than no motor.

I think I actually have several of the cruise control bits. I now have 4 injection pumps, although I think I sold one of the whirligigs a while back on eBay.

[Dirty Duc]

Well, it seems the donor car was likely in the junkyard due to a hamfisted timing belt swap and then a series of other "fixes" that generally added up to a non-running car.

It looks like someone attempted to change the timing belt using the "dot" method of alignment. It was a tooth off. Remedied that using tools (and the Porsche bell housing that is very easy to remove from the car).

Started to check injection pump timing, and realized the fuel injection pump is not right. The plunger only travels .70 mm! Luckily I have a spare boost-compensated one (Bosch probably has different words, but I can't remember them right now), and due to the way I am misusing this engine even a non-compensated pump will work.

It looks like somebody has replaced the turbo at some point. We'll get it set up using the right tools (I should check the torque on the crank pulley) and fire it up before we put it in the car.