IMS Bearing failure recovery and cylinder head condition
08-13-2018, 09:39 PM
#16
Burning Brakes
Back to the original question: Based on my experience, I think there’s a good chance your heads and cams are fine. The car I bought had a major failure of the number 6 connecting rod bearing. I don’t know how long the previous owner ran it, but it had glitter in the oil canister, glitter and chunks of bearing material and steel in the sump and stuck to the oil intakes. The con rod was running metal to metal on the crank, and the crank was heavily scored.
I had the same concerns as you, so sent the heads and cams to Hoffman and asked him to check them and give me his opinion. He cleaned them, did leak tests and pressure tests, and surfaced the gasket surfaces. Bottom line was the cams and bearing surfaces, and valve guides were in excellent shape, in fact he told me he’s seen heads in much worse condition from engines that had not suffered a failure. I installed them into a new short block and the engine is running perfectly.
I had the same concerns as you, so sent the heads and cams to Hoffman and asked him to check them and give me his opinion. He cleaned them, did leak tests and pressure tests, and surfaced the gasket surfaces. Bottom line was the cams and bearing surfaces, and valve guides were in excellent shape, in fact he told me he’s seen heads in much worse condition from engines that had not suffered a failure. I installed them into a new short block and the engine is running perfectly.
08-13-2018, 09:42 PM
#17
Burning Brakes
The crankcase is actually connected to the heads by the cavity for the chains. I had metal from the crankcase get into the heads while using a no bypass oil filter.
Posters should be be a little careful with absolute opinions, especially when they are absolutely wrong.
Posters should be be a little careful with absolute opinions, especially when they are absolutely wrong.
08-13-2018, 10:23 PM
#19
Burning Brakes
Coopduc, if your post was addressed to my last post, just wanted to clarify my post was not addressed to you specifically.
Saying a failure in the crankcase absolutely does not affect the heads is wrong and I think it would be wrong to lead listers to believe so. Yes, you can gamble, but anyone repairing their engine should know there is a pathway for debris to get into the heads. IIRC, the detergents in the oil actually captures/carries debris to take it to the sump as opposed to break in oil which allows debris to drop out.
An engine rebuild is expensive and is a good example of insanity. So everyone that partakes in dong so should at least know what the risks are so there isn’t a second failure sooner than expected.
Saying a failure in the crankcase absolutely does not affect the heads is wrong and I think it would be wrong to lead listers to believe so. Yes, you can gamble, but anyone repairing their engine should know there is a pathway for debris to get into the heads. IIRC, the detergents in the oil actually captures/carries debris to take it to the sump as opposed to break in oil which allows debris to drop out.
An engine rebuild is expensive and is a good example of insanity. So everyone that partakes in dong so should at least know what the risks are so there isn’t a second failure sooner than expected.
08-13-2018, 10:24 PM
#20
08-13-2018, 10:42 PM
#21
Burning Brakes
@tomcat - understood, no issue from my side. In any event, heads and cams absolutely should be checked after an engine failure, but not automatically assumed they are damaged.
08-14-2018, 12:50 AM
#22
Rennlist Member
I'm in the camp of the heads will be ok. No need to squabble about it, no one will know until it disassembled and inspected/measured.I've been a dealer Tech for over 40 years and have seen the inside of many engines with debris of all kinds and all amounts. Debris usually kills the rod bearings or main bearings first, the heads usually survive (unless there is a catastrophic failure like broken rod or dropped valve). What usually kills the heads is dirt or very small debris, less than 10 microns (that the filter will not catch anyway) over a long period of time that will wear the in-head cam bearings.
08-14-2018, 05:43 AM
#23
Its true that marketing is often deceptive, but in this case, the LN Engineering folks are widely recognized as experts on these engines. If you search in the threads, there is discussion with pictures related to the design of the stock porsche oil filters.
There is history on the design too. I have a porsche 356 with a paper filter. The 356 engines are based on the old VW engines. They also have bypass flow. There are also adapters you can buy for the 356 to install modern oil filters, although I don't think LN Engineering sells those.
There is history on the design too. I have a porsche 356 with a paper filter. The 356 engines are based on the old VW engines. They also have bypass flow. There are also adapters you can buy for the 356 to install modern oil filters, although I don't think LN Engineering sells those.
Which is why I think OP's heads have a good chance of being fine. @tomcat, nowhere did I say his head will absolutely be fine so don't put words in my mouth, thanks. The chain-pathway is a possible one, I addressed the pressurized path from the oil filter though. Afaik the cams are pressure fed, so debris will not flow upstream of that. How is that an 'absolute opinion'.
It is possible to be widely recognized as experts and be a business at the same time you know.