00 MRS - 2ZZ NA
Unless your block was done 100% right by a good shop, do compression checks every once in a while...
Buyer beware: MWR sleeved blocks - NewCelica.org Forum
Buyer beware: MWR sleeved blocks - NewCelica.org Forum
Back in the spring of 2006, I assembled a new engine based on a Monkeywrench Racing sleeved shortblock. Ever since startking the engine, I've had constant overheating problems with the engine. I have quite a long detailing my attempts to figure out why the engine was overheating.
How is air getting in my coolant system? - NewCelica.org Forum
Initially, I thought the reason for the trouble was an improper installation of the thermostat. There is a small check valve in the thermostat that is suposed to go at 12 o'clock to allow any trapped air bubbles to pass. This turned out to not be the problem.
After that, I went through absolutely everything possible to verify that I hadn't made some mistake in the install. After an extremely long search, I found one other debatable issue with my engine build. Although I had torqued the ARP head studs to spec, I did not know at the time that ARP had a whole procedure listed on their website for the installation of the studs that went far beyond simply installing them and torquing to spec. So in spring 2007, I retorqued all the head studs and considering that the car had overheated on more than one occasssaion, I exceeded the ARP recommended torque spec.
The engine actually held together great for about five months after that. With the increased head torque, the car seemed to have stopped consuming coolant and although I never ran the car at full throttle for an extended period, I did do a number of full throttle back-to-back runs with no issues.
Then one day driving to work last September, the car just started misfirng badly while under medium load. When I got the car home, I pulled the plugs and found that #1 was completely clean and the insulator was cracked. The coolant overflow bottle was also completely empty, so coolant was being drawn into cylinder #1. I assumed that after overheating several times, the head gasket was simply compromised and that it finally just popped under normal driving conditions.
So the car sat all winter but last weekend I pulled the motor and just today started tearing down the block. What I found to be the actual cause of the failure was not the head gasket but the sleeves in the block dropping. The sleeves had dropped on cylinders 1-3 but somehow, cylinders 2 & 3 were still sealing well enough to not cause major problems. All the overheating issues with my engine have now come into perspective. With a very poor head seal due to the dropped sleeves, I now understand why there was massive overheating problems when under prolonged high load. I was also seeing knock under these conditions but not elsewhere, despite running very conservative ignition timing for my setup (17 degrees timing max, 93 octane, 10:1 compression, 9 psi boost). Its possible that the exposed head gasket edge was creating hot spots that were inducing knock under extreme conditions. Looking at the spark plugs at other times, cylinder #4, where the sleeve did not drop, always had a different appearance to cylinders #1-3.
So considering that #2 & 3 continued to seal despite the dropped sleeves, I have doubts that any of the sleeved blocks are holding up? I'm not sure if this is a Monkeywrench issue or an issue with the dry sleeving process in general. I now know of at least three of these blocks that suffer from the same problem. My block was made is early 2006 and I was told at the time by Matt that they had switched machine shops due to the first shop not knowing what they were doing and ruining blocks. So this isn't an "early block" issue that I know has come up.
At this point I'd recommend people stay away from these blocks lest you want to chance running into the same debacle I have. A this point, I basically have a super expensive boat anchor sitting in my garage and I'm going to need an all new block.
At this point I would higly reccomend paying the $1800 for one of LRs bombproof blocks (that includes the sleeves). Those sleeves are shouldered in 2 places and cannot drop - its not possible. They also have coolant flow between the cylinders.
MWR now sends all their blocks to Darton to be sleeved. In the past, they'd used a variety of shops around their area to fit the sleeves. I have one of those blocks. The dropping sleeves was a well-known problem with early MWR blocks, but supposedly that problem was solved by switching shops. Apparently not. My biggest concern about these blocks in general is that two of my cylinders were still sealing despite dropped sleeves. That makes me think that there are more blocks like mine out there.
I don't 100% trust the idea of the dry sleeves. With a steel sleeve and aluminum block, you have two metals that expand differently when they get hot. The aluminum surrounding the sleeve could theoretically expand more, causing the head gasket to lose sealing against the sleeve. That would actually explain my overheating issues under extreme conditions. I think I'd be more comfortable with the entire sealing area being the same metal.
I'm not necessarily faulting MWR here. But here are a few things I can tell you:
1. MWR has admitted that they had issues with their original shop who was sleeving engines. My block was made in April 2006 and was not done by the original shop.
2. MWR has switched shops again from their local machine shop to Darton (presumably Darton East in Indiana).
You don't switch suppliers when you're happy with the work you're getting. You also don't ship a large and heavy item like a block if you don't have to. MWR has no direct control over the quality of their sleeved blocks, but the supplier switch to Darton tells me that they're aware that the "new and improved" shop that did my block is problematic. I wouldn't blame Matt for not making that info public if he had it. I worked in the service department of an engine distributor for two years and we didn't exactly start phoning up our customers if we discovered a problem that affected engine that were already in the field. We dealt with them as they came up on a case by case basis.
I'd like to point out that I have no direct experience with dry sleeving and what I posted is speculation based on my semi-extensive knowledge of materials science.
Cliff Notes: Dry sleeves from MWR and non-MWR blocks have been dropping, so it looks like Darton themselves are going to be the number one installers of dry sleeves instead of your local machine shop that could mess up. I guess there WAS a reason MWR ran 500+ whp in their old daily driven GTS, and 666+ whp in their drag GTS with only Mahle 9:1 drop in low compression pistons on an open unsleeved deck...