rust on cylinder wall

[jonnyturbo]

Started as a BHG. White smoke coming out the exhaust, over heating, coolant mysteriously disapearing and showing up in the oil. I was in the Navy and didn't have the time, nor did I want to have someone else do the job, so I put it off.

Finally got the time and oportunity to work on it and I wanted to ask a couple questions.

1. The head gasket came off in one piece and I can't see any obvious place that the gasket failed. I was assuming that I would have to spend some work just getting the gasket material off the head/block. Is this normal and does this help anyone know why the gasket failed?

2. When I got the head off the was a little bit of rust on the cylinder walls. A light red dusting on parts of the cylinder wall. I ran my finger nail over it and I can't feel anything, but I wanted to know if anyone had a guideline on when you take the engine to the machine shop and when can you just put things back together?

I'm not against a rebuild and I know that it's going to happen sometime in the future, but the question is do I need to do it now or can I get some more miles and time to raise funds for a better rebuild?

Thanks everybody

 

[7Mboost]

BHG is common your gasket failed welcome to the 7m. And as far as rust on the block, you need to check for scoring and a lip/edge on the cylinder walls. Best thing would probably take it to a machine shop to inspect it.

 

[starscream5000]

You will have to replace the rod and main bearings to prevent rod knock due to the fact that there was coolant in the oil, which in turn becomes acidic once the oil and coolant mix and heat up. Your bearings are on they're way out wether you know it or not . Make sure when you get new bearings, to have the con rods resized where needed and proper sized bearings are ordered for each main and rod . This would be a good time to have a thurough inspection done on the internals (condition of rods and pistons). Might as well replace the oil pump (cheap insurance).
Oh, and to answer your questions :

1. The head gasket probably failed IF it was the original because of the improper torque values on the bolts like Toyota made them from the factory. If you're going to do it, I suggest using a metal head gasket (here on out reffered as MHG) and hace the head AND block machine so that they are both flat again and as smooth as possible (Roughness Average of 15 or less. Most MHG companies require an RA spec around 20-25, do the research for your specific brand. The lower the RA spec, the better ). Also, ARP studs are a great asset to invest on the engine at this point (torque to ~81 ft/lbs. with ARP moly lube).

2. If the cylinder walls are ok, you could get away with cross hatching the cylinder walls and re-ringing the pistons. If the walls aren't good, you're looking at an over bore, might as well get some good piston at that point in time .

Trust me, if you're going to do this, do it once and do it right so you will not have to worry about it again . I can't stress how important it is to replace the bearings on an engine that had BHG.