Does anyone do a compression check as pre purchase inspection?

[Coyote machine]

Your to funny

I am. And FWIW, for future reference, the 'to' you are using is with two 'o's, as in too funny. Or two guys walk into the barn, and I'm going to Jefro's house Ma, after I clean out the barn stalls.

 

[Coyote machine]

It really doesn't matter, the question remains. Does anyone do a compression check as pre-purchase inspection?

It's a very simple question. Useful replies could add to the information on how to evaluate any engine's condition.

From the replies, I think not many have ever done a compression check, nor would know what values were meaningful if they did.

Myself, I like to put a vacuum gauge on any normally aspirated multi cylinder engine. Chain saws, I can tell all I need just by pulling the cord. ;-)

On a Compression ignition engine, it is often easiest to gain access by way of the pre heaters. No messing with the fuel system that way. Be sure to hold the fuel cut off closed when cranking for the compression reading!

Pre-heaters are commonly referred to as glow plugs, and in this case you're wrong; I for one am very familiar with diesel engine compression tests, and still have the gear to perform them when needed. But the best way to get a sense of engine condition is to do an oil sample analysis which is relatively cheap, and a good predictor of general engine condition based on knowing the # of hours and general use of the engine in question. Yes one could do a diesel compression test if warranted, but condition can be seen/heard, smelled, if smoke is present at startup from cold condition and listened to during warm-up. Diesels do tend to mask some adverse engine noise if the fuel injectors are misfiring, dirty or noisy. Mis-adjusted IPs can also make a diesel run crappy. (Injection Pumps=IP).

IMO, oil analysis is more effective than a random compression test, and more likely to be acceptable to a seller to take a sample of oil from the crankcase than the more invasive compression test procedure.
My shop routinely dealt with Mercedes Benz diesels, BMW and VOLVO. Occasional VWs, but mostly the turbo diesel Benzes. We ran few, but some compression tests, as needed. With the exception of needing frequent oil and filter changes, especially during the winter months, and 'cut' fuel, they ran pretty flawlessly. Occasionally radiator header gaskets and climate control modules would blow up, but not every day.

 

[4570Man]

I am. And FWIW, for future reference, the 'to' you are using is with two 'o's, as in too funny. Or two guys walk into the barn, and I'm going to Jefro's house Ma, after I clean out the barn stalls.

Don’t forget. It was you’re.

 

[Coyote machine]

Don’t forget. It was you’re.

As an abbreviation, yes, in my case, I wrote out the words and chose not to abbreviate. And its definitely NOT 'your' as so many use when they mean; 'you're' dog ate the service manual.

English ain't easy, but American usage is complete butchery, IMO. :confused3:

 

[countrybumpkin]

I know, but it drives you crazy when people say it that way.

 

[moriboy]

I haven’t done a compression test at the time of purchase. However, had I done one on a particular truck years ago, I probably would’ve bought a different truck. I was 15 and learned a good lesson!

 

[CalG]

Thread death!

When the GUM (Grammar, Usage, and Mechanics) police start in, there is nothing more that can be shared.
Thank god for the spoken word! True communication with eye and face expression and emphasis through hand gestures.

 

[4get gto]

Thread death!

When the GUM (Grammar, Usage, and Mechanics) police start in, there is nothing more that can be shared.
Thank god for the spoken word! True communication with eye and face expression and emphasis through hand gestures.

Ain't that the truth. There being two funny

 

[Jstpssng]

I wouldn't do it, or allow a potential buyer to do one for some of the reasons mentioned above. If the price is right sometimes you have to take a chance. Both of my Kubotas have been purchased from dealers for that reason; they offered enough of a warrantee so that you can test it out and tell if there's a problem.
As for the grandma police, their seams two bee moor of a personal conflict than anything; I think that wee all new what the posts weir trying too say.

 

[CalG]

;-)..................

 

[Coyote machine]

AHHHHHHHHA! Youse guys so funny, makes me laugh. Police NOT, someone who respects one's native language, yes! Just the 3 ways to say to, are meant to clarify, not confuse our written language. If one doesn't care, or is too stupid to be able to construct simple sentences, well good luck conveying what one means to say. Even with club and fire stick to show one's high level of skills grunting and pointing to rock in road. Ugh, ouga-booga, me make faces to say what me need to, wave arms too, I got two arms, me know stuff. Right stuff on cave wall, find woman, have mo' cusins to play doctor with. Drink beere, fall down. Life good, smart peeps only lefties, fearless leader said sough!

 

[CalG]

Wu!...................

 

[4get gto]

Got me thinking again. What a Friday this is gonna be.
Do I not care or am I just stupid.

 

[Jstpssng]

I pick up on those little errors also, I just don't find them noteworthy. I'm pretty good with grammar and spelling, while others are much more adept at other things. I wish that I was as talented at mechanical as some of the other posters here. Is it more important to be able to spell crankshaft; or to be able to strip a dead engine done to said part, then put it back together properly?

 

[mykleh]

back to the actual question.. I do it on two strokes.. snowmobiles actually.. everything else two stroke I bought new.. to pull a sled plug is very straight forward and pull over a couple times repeat done...

 

[Texasmark]

I do. Recently purchased the 3910. Ad said 898 hrs. By the time I got there it was reading 901......ok fine. Actual. Checked the brake and clutch pedals and paint hardly worn off, much less metal worn off. Ok fine. Actual hrs, one owner, mowed his pasture with it....looking good.

It was an estate sale and I made arrangements with the sales guy to meet him at the estate the next day. I was there with my trailer. He comes up, walks over and hands me the key.......that there tells me it hadn't been run in at least 24 hrs so it would be a cold start, meaning if low in compression it would show up easier than if he had had it running right before I got there. I stick the key in the switch, roll it over and before I can get my fingers off the key the diesel was purring like a kitten at idle no less. Yepper actual hrs, one owner, tin and paint are original and nice, new rubber all around......now, what's it going to cost me?

Told him for x bucks we can put it on the trailer....x bucks was 2k below his asking price. He said the lowest I could go was a number 500 bucks above my offer. I said let's load her up.


Diesels get their "spark" via hot air in the combustion chamber that only gets hot by compression. If you have good compression you can barely roll the engine over and it will light right off......which it did. Wink.

Conversely, I bought the 3000 in April in Texas (plenty warm in April in Texas) and the seller (flipper actually) had to whip out the ether before it'd start.......guess what; engine worn out. I had been looking for one for a long time and was overwhelmed at finding one.......lost my good sense. I should have known better or should have paid him a lot less for it. But I paid his price and later after realizing the problem, did an inframe for about $1k and that was 30+ years ago. Have done nothing to it since to speak of other than normal things. So it turned out to be an ok deal after all. You never know.