Blown head gasket - do whole engine?

[bjudd]

Blew head gasket... Head was too thin for surfacing. Found used head.

Two estimates for head repair $8,000  (plus what I paid for the used head.)

Second option:  Send whole engine to Metric in Canoga Park & do all the necessary extras... $17,000 for removal, re-install, hoses, lines, etc.)
Doesn't include refurbishing of fuel injection and likely de-grease and paint of the engine bay. (Car was painted a few years ago with engine in... didn't touch the engine bay.) 

Visited another reputable SF bay area shop today that will do the whole engine, fuel injection $18,000 (he insists on sending the fuel injection pump out because of the new block.)  20k with engine bay clean/paint, etc.

Is it foolish to do only the head? Both shops recommend doing the whole engine.

Are these prices in line?

Input?

Thank you.

[StevenF]

Bjudd
Who told you 17,000 at metric?
Does't sound right
Steven

[dirkbalter]

Bjudd,
I agree, it doesn't sound right. When I talked to Metric Motors ( 2 years ago), we went through different scenarios and came up with 4.5k for a rebuild short block or about 8.5k for the complete engine / head. (230or 250sl)
Dirk

[bjudd]

Apologies for the lack of clarity...

The motor from Metric is $9400 retail  (9000 for a shop) .. $10,500 with my shop's markup.

17,000 was for aborted valve job & machine shop inspection (almost a grand), removal,crate & send to Metric.hoses, belts, plugs, distributor cap/rotor, coolant, trans fluid, water pump, bypass hose, thermostat, points, condenser.. & labor (3,400).   He did not include rebuilding the fuel injection.

The other estimate is $18,000 includes all the above and fuel injection rebuild. (additional 1,500 to paint engine bay while the engine is out.)

[Cees Klumper]

Those are large numbers. Are you sure the head you bought needs anything done to it, or could it not just be fitted to see how the engine performs with it as-is? Same with the bottom part - what makes your mechanic advise you to rebuild it? If the head seems in ok shape, I would just fit it and see what happens before spending close to $20K. Of course getting it all done can't hurt so long as it's done by professionals who know what they are doing, such as Metric.

[stickandrudderman]

I certainly would not fit a used head without first installing new guides and seals, re-facing the valves and skimming the face. Also check for corroded water jacket plugs and any damaged threads that are better repaired on the bench than in the car.
As for the rest of the engine; if it was running fine before I would leave it alone unless there's any visible signs of defects n the bores when the head is off.

[bjudd]

The used head does need to be gone over for all the things mentioned by stickandrudderman. It has thickness to allow for milling as needed.

I'm being told that the increased compression from the new head could put pressure on the bearings & rings... so do it all now. (accurate?)  Also, it allows me to check the clutch (which has shown some indication of wear.)

 

[Cees Klumper]

Don't have the head skimmed unless it's absolutely necessary (why would it be?). It can only be done a few times before the head is scrap. Some rebuilders do it as a matter of standard operating procedure, but if it's not needed ...

[Benz Dr.]

We try to straighten the head first then take a light cut from the bottom of the head. We also mill the top of the head as most of them are anything but level. Everything needs to be removed first like valve guides, studs, dowel pins and casting covers. I use cam shims to take up the extra distance needed for rocker geometry when anything is removed from the thickness of the head or valve seats.

A thing to note: measurement of 84.00 mm min. for head thickness may be reached and the head will still be perfectly OK if material was removed from the top and bottom of the head. If top is milled, you should get the total amount removed and add that amount to come up with the total head thickness. 

[Shvegel]

I have never understood the argument that somehow doing a valve job or slightly shaving a cylinder head causes the bottom end and rings to wear out appreciably faster.  I you think about it the engine is still simply experiencing small explosions of fuel and air.  having a valve that is somehow tighter isn't going to effect that much.  In fact machining the valve seats without shaving the head actually causes a net drop in compression.
The rule of thumb is that peak cylinder pressure is 1000 times the compression ratio so a 9.5 to one compression ratio would yield a peak pressure of 950 psi so if you shaved the cylinder head and increased it to 9.7 to 1 your peak cylinder pressure would be approximately 970 psi.  Slightly less than 2 percent increase in cylinder pressure.  Big deal.

[ja17]

I always try just the valve work first before a total rebuild. I closely examine the cylinders, sometimes I remove the oil sub-pan and remove one or two pistons for close examination. during the process some rod and some main bearings are spot-checked. 90 percent of the time, an engine's first head reconditioning will solve any of the oil burning and smoking issues. I break down the cylinder heads myself so I can see what issues are apparent. (bad or loose oil seals, loose or worn guides, leaky ball adjuster bases, etc.)

[Mike Hughes]

A blown head gasket often results in an overheated engine - or was caused by one.  The iron block is much less likely to warp than the aluminum head.  If your head is toast because it was skimmed too much then s competent machine shop will check a replacement head to make sure it is true before doing any machine work and dress the gasket surface as minimally as possible, if necessary.

Last year it cost about $2400 to R&R the head, replace guides, a couple of valves, the cam gear, associated machine work, etc.  My problem was excess oil consumption.   The Pagoda runs like a champ and will be at PUB.

About 7 years ago my 86 XJ-6 4.2 L twin-cam engine blew a little bypass hose, overheated and blew the head gasket.  It cost about $4200 to R&R the head, true the warped head, replace guides, a couple of valves, some followers associated machine work, etc.  The machine shop barely had to touch the gasket surface because the warpage was corrected so well by the specialist who did that part of the work.  The Jag has over 150K on the odo and the bottom end has never been touched, oil consumption is nil and it runs like a top.

Just because the top end has been damaged doesn't mean that the whole engine needs work.

[Benz Dr.]

A blown head gasket often results in an overheated engine - or was caused by one.  The iron block is much less likely to warp than the aluminum head.  If your head is toast because it was skimmed too much then s competent machine shop will check a replacement head to make sure it is true before doing any machine work and dress the gasket surface as minimally as possible, if necessary.  The Pagoda runs like a champ and will be at PUB.

Last year it cost about $2400 to R&R the head, replace guides, a couple of valves, the cam gear, associated machine work, etc.  My problem was excess oil consumption.  About 7 years ago my 86 XJ-6 4.2 L twin-cam engine blew a little bypass hose, overheated and blew the head gasket.  It cost about $4200 to R&R the head, true the warped head, replace guides, a couple of valves, some followers associated machine work, etc.  The machine shop barely had to touch the gasket surface because the warpage was corrected so well by the specialist who did that part of the work.  The Jag has over 150K on the odo and the bottom end has never been touched, oil consumption is nil and it runs like a top.

Just because the top end has been damaged doesn't mean that the whole engine needs work.

That depends on a couple of things:
a )cylinder wear and if there's any cross hatch left
b )how many miles are on the the engine
c )what kind of oil pressure you have at hot idle

Heavy cylinder wear is a general indication of overall engine wear. If you also have lots of miles on the engine in excess of 130K and you have low oil pressure at idle, you would be fooling yourself if you didn't at least have a look. Even one bad bearing can result in lowered oil pressure and if it's a rod bearing you won't go far.

[Mike Hughes]

Good call, Dr. B.  In both my cases there was good cross-hatch and little or no discernable ridge.  Oil pressure at idle was not a problem.  Mileage was in the 80's on the Pagoda and just under 120 on the Jag and both cars have been well maintained and pampered since they were new.  The folks recommending doing the whole engine for Bjudd may be looking at an entirely different set of conditions - we who are commenting may not be in possession of all of the facts.

[Shvegel]

I rarely question another shop prices but $8000 for a head repair?  Even if you spent $2000 on rebuilding the used head and parts which would be a stretch that is still in the neighborhood of 50 hours of labor?  That sounds like double the price of a blue chip bolt polishing job.