1994 Protour 190 Restoration

[waterlogged882]

The engine only had 775 hours it would crank right up and appeared to be running properly. The plan was to do a leak down compression test and a visual inspection now that I had it out of the boat if it passes clean it up and repaint it.
Things do not always go as planed it failed the compression test cylinder #1 was low.
New plan take the engine apart and figure out what is causing the low compression on #1.

Last photo tells the story (obviously). Wonder where the rest of the ring got off to?

Are the walls in that cylinder scored?

Is there a crack on the piston head?

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[RDahler]

The rings were intact as well as the broken ring land at first I did not notice it was broke. when I removed the compression rings the ring land just fell out. There was no scoring and the rest of the piston looked normal. The cylinders were standard I ran a Bore Gauge threw all the cylinders and they all fell with in OEM service specifications. I also checked the ring end gap it was in the middle of the spec. I think root cause of this broken ring land was caused by a over heat event and one of the compression rings end gaps expanded and touched. A contributing issue I found all the 1/4 inch water metering holes in the head gaskets were plugged with shards of old water pump Impeller blades. The LT1 might benefit from some kind of a strainer to trap the water impeller broken blades.

[waterlogged882]

The rings were intact as well as the broken ring land at first I did not notice it was broke. when I removed the compression rings the ring land just fell out. There was no scoring and the rest of the piston looked normal. The cylinders were standard I ran a Bore Gauge threw all the cylinders and they all fell with in OEM service specifications. I also checked the ring end gap it was in the middle of the spec. I think root cause of this broken ring land was caused by a over heat event and one of the compression rings end gaps expanded and touched. A contributing issue I found all the 1/4 inch water metering holes in the head gaskets were plugged with shards of old water pump Impeller blades. The LT1 might benefit from some kind of a strainer to trap the water impeller broken blades.

Interesting and thank you for the note.

So are you going to bore over or rebuild to stock?

Do you happen to have a photo of the clogged water metering holes?

This is good stuff right here.

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[2RLAKE]

wow ... love this thread!!!!

[RDahler]

Interesting and thank you for the note.

So are you going to bore over or rebuild to stock?

Do you happen to have a photo of the clogged water metering holes?

This is good stuff right here.

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The engine was in very good shape for it's age. I just ball honed the cylinders they came out looking like new. I did not want to upset the factory balance on the rotating assembly I was able to buy a good used standard piston and rod assembly off the same year model corvette LT1 engine on ebay $30 this was a win made the decision to go back stock the best choice. I soda blasted the top's of the pistons and the ring groves to remove all traces of carbon this made them look like new.
I removed the freeze plugs and cam bearings and power washed the block. I scraped all the scale from The inside of the water jacket and removed more impeller blade shards wedged between the cylinders.

I did not take any pictures of the old head gaskets.

[bret]

Did you take any pictures of the head resurfacing you completed, when you worked them back and forth for a FLAT surface?

[RDahler]

Did you take any pictures of the head resurfacing you completed, when you worked them back and forth for a FLAT surface?

The Heads were a challenge I went old school and broke them down for inspection cleaning and rework. bagged and tagged each parts location so they would go back in the same spot. Soda blasted the heads inside and out. Inspected all the parts. replaced three exhaust valves , five weak springs and 16 valve seals.
Aluminum Head do not get along very well with cast iron blocks they almost always come off a little warped over heating makes this worse, They measured .006 and the max is .004.
I constructed a lapping table out of a 1/4 plate glass on top of a 3/4 mdf board with a wood frame to keep the glass in place. Used spray adhesive to secure the sand paper. I used three different grades of sand paper. I was able to deck the heads to less than .001 in all directions. Hand lapped all the valves and reassembled. Used a hand held vacuum pump and a small plate with a rubber gasket to pressure test each port.

[waterlogged882]

Nice work. Thanks for sharing and taking the time to post up here.

Very interesting to see all of this come together.

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[MIskiboat]

1994 Protour 190 Restoration

This is awesome.
Suggest adding remote mount oil filter. The LT1 is not easy to change, as it is in the back right against the trans.

[RDahler]

This is awesome.
Suggest adding remote mount oil filter. The LT1 is not easy to change, as it is in the back right against the trans.

I was feeling your pain the oil filter it had the large PF-1218 filter on it and the original splash/dust cover had a 1/4 inch lip bent out just right to collect the oil when you remove the filter and deposit inside the bell housing. I looked at adding a remote oil filter but there just not a good location for it.
I bought a new Indmar splash/dust cover PN 535047 $15.38 from Inboard Online.
I did the LT1 Mod cut the ear off the new cover with a band saw smoothed and painted the edge.
Installed a new AC/Delco PF-454 filter the OD is smaller now so there is more than enough room to slide a plastic container up on the filter and no more oil in the bell housing.

Problem Solved.

[MIskiboat]

^^^. That will be better for sure. Still a little tricky. Nice work.

[2RLAKE]

fantastic work ... can't wait to see this in the water

[edwin]

Truly impressive work...great thread, and thanks for documenting and sharing!

[RxMC]

I see the boat says ProTour on it. How are the hull and engine different than the ProStar 190?

[RDahler]

Mastercraft 1994 Protour 190
This is the way Mastercraft describes it in there sales brochure.